In memory of
YULIYA STANISLAVOVNA BOYARSKAYA,
founder of the moldavian scientific school in physics of strength and plasticity,
recognized in many scientific centers of USSR,
Community of Independent States and foreign countries.

The short presentation of the main scientific results, some biographical details and recollections are dedicated to the seventy-fifth anniversary of the birth day of Yuliya Stanislavovna Boyarskaya, who was a soviet and moldavian physicist, professor in the field of solid state physics and universitary professor, doctor habilitat in physics-mathematical sciences, organizer and permanent head during 35 years, 1961-1996, of a scientific group and of the laboratory of the Institute of Applied Physics (LAP) of the Academy of Sciences of the Republic of Moldova (ASRM).

Yuliya Stanislavovna Boyarskaya, 1970

of the thesis was determined as "The investigation of the thin surface layers of the solids by the methods of microindentation and scratching". It was supposed to establish the correlation between the hardness of the solids, their structure and surface energy. The equipment consists from the PMT-3 instrument for microhardness measure and the metallographical microscope MIM-7. Yuliya Stanislavovna proposed to employ the PMT-3 not only for the deformation by pressing, but also by scratching. Soon she realized that the elastic restoration of the imprint, which appears after the removal of the indentor, influences essentially the value of the microhardness. By combining the functions of two instruments in one more complicated construction she succeeded to measure the parameters of the recovered and not-recovered indentations in the case of transparent materials. The elastic recovery effect was studied in details. On this way was established that the indentation forms are different for different materials and even depend on the orientation of the indentation's sides as regards the crystallographic directions of the sample. The more microhardness was, the more elastic restoration appeared. It happened that the new method is even more needed for fragile materials, because of the cracks formation around the imprints and their strong destruction under deformation. Already from the first steps in the post-graduate studies the main features of the creative style of Yuliya Stanislavovna were revealed. Among them the permanent interest to the investigated processes, the ability to propose their clear and simple models and explanations. But soon the supervisor left Kishinev and it was necessary to continue the work alone, without the possibility to ask somebody or discuss with the specialists the arising questions.
Later on remembering her post-graduate studies and her becoming as a scientific worker, Yuliya Stanislavovna always regretted, to have not the possibility to pass a serious scientific training in one of the great scientific centers of Moscow, Leningrad or Kiev, where in the atmosphere of common seminars, discussions and investigations the young scientific collaborators are formed.
Nevertheless, even in the confined scientific space of KSU in that period of time, she continued her way of a self-taught and pioneer in microhardness. As a result to the end of the post-graduate course she succeeded to remove many contradictory opinions existing in literature concerning the mechanical properties of the crystals revealed by the methods of sclerometry. Two effects such as the elastic recovery and polar anisotropy of the scratches and microhardness formed the base of her candidate dissertation named as "Investigation of the microhardness of the crystals by the method of indentation and of their anisotropy by the method of scratching". The thesis was preliminary approbated at the scientific seminar in the Institute of Crystallography of the Academy of Sciences of USSR (ICAS) in Moscow in the laboratory of Mechanical Properties of Crystals headed by professor Marina Victorovna Klassen-Neklyudova.

At the beginning of March 1955 Yuliya Stanislavovna unanimously defended her candidate thesis at the Scientific Counsel of ICAS, being presided by the academician A. V.Shubnikov. She went alone to Moscow being pregnant, three months before the birth of her daughter Elena. After the defense she expressed her gratitude to professor M.V. Klassen-Neklyudova and to her collaborators for the assistance and returned to the flat where she was living, none suspecting that such event merit to be celebrated. Yuliya Stanislavovna was the first woman doctor in physics-mathematical sciences in Moldova and one of the first three doctors in this field between the post­graduate students of KSU. Returned to Kishinev and being a modest and unpretentious person, she did not underline her achievement, while for the most of us, her colleagues who together graduated KSU it was a dream. For me, for example, who worked first five years in the Kishinev Agricultural Institute, before the post-graduate studies in Kiev, this dream was realized in 1960 during the "Khrushchev thaw". One can note, that the candidate scientific degree is equivalent to the Philosophy Doctor degree in the western countries and to Doctor degree in Republic of Moldova. The candidate dissertation stimulated the interest and opens the possibility to get deeper knowledge in this field of condensed matter physics. Step by step this interest and investigations transformed into the activity of all her life, to which she remained fidel. Academician V.L.Ginzburg once noticed, that the science takes revenge to those, who betray it, consigning them to oblivion. Yuliya Stanislavovna never betrays to the chosen area of science, with which she happened to meet at the beginning of her post-graduate studies, while in that period of time it was a very difficult region of the solid state physics. More so ,together with her collaborators, disciples and followers, she made an incontestable contribution to its development. This contribution as well as the efforts of several generations of physicists, who worked in many laboratories in the world, lead to the radical change of the state in this field. Possible some words concerning the specific aspects of this area of investigation are needed.
Non-homogeneous strained state arising under indentation generates a great number of dislocations and accompanying processes. If one would compare the processes, which take place under the action of the machine "Instron" generating the homogeneous strength with the deformations appeared under indentor, one could observe some analogy between the crystalline and liquid states. In the first case there exist the clear, beautiful models of lattice oscillations and band structure of the electron states, whereas in the case of liquid the long-range order is absent. By this reason the theory of liquids does not contain so simple and accessible models and remains one of the most complicated area of the condensed matter physics. Yuliya Stanislavovna understood very well the difficulties of her way, but she did not lose the courage and the hope to get over all the adversities and the misfortunes related with the scientific work in this field. The acknowledgement of the merits of the scientific school created in Kishinev in this direction will arrive much later, when the physics of micro-indentation will become much more solicited. One of such recognitions will be the session in departure of the Scientific Counsel of the Academy of Sciences of USSR on the problem "Physics of Strength and Plasticity" held in Kishinev in 1986. But in the present time it was only 1956 and up till the eminent session it was necessary to pass a difficult but fruitful ascendant way as long as 30 years. Returning to 1956 year one can remember one important event in the life of Yuliya Stanislavovna. Professor Yu.E. Perlin, the chief of the chair of theoretical physics of KSU, invited her as a senior staff member. She worked as a docent of the chair during five years up till 1961, delivering normative and special courses. This five years period was very responsible. It needed a great preparatory work, but at the same time it promoted to the formation of the high level qualification. Many of the present collaborators of the Academy of Sciences and of the Universities of Moldova remember with respect the lectures delivered by her. She had been prepared to the lectures carefully, delivered them clearly, quickly and enthusiastically, trying to captivate the auditorium by the beauty of the discussed physics. But the scientific work she continued in the previous direction, trying to use the new knowledge and accumulated experience for the theoretical explanation of the experimentally observed deformations. Some graduate students of this chair, for example M.I.Val'kovskaya, R.P. Zhitaru and S. S. Shutova and other became in consequence the first members of the forming scientific group, the first candidate of phys-math. sciences in this field belonging to a new generation. They as well as the graduated students of KSU from another chairs and even somebody from other universities including D.Z.Grabko, M.S.Kats, M. Dyntu, M.A. Linte, N. A. Palistrant, M.I. Medynskaya, V.A. Rahvalov and other have prepared their theses under the supervision of Yuliya Stanislavovna or became the first collaborators of the future laboratory. More so D.Z.Grabko and R.P.Zhitaru became the first doctors habilitat belonging to new generation. At the present time they together with another, else more younger generations become the main leaders, followers and representatives of this scientific direction in Moldova. One can see that the activity of Yuliya Stanislavovna in the frame of the chair of theoretical physics permitted her to select and to attract in science young people side by side with the rising of her scientific level. This period of life became complicated for her else by the fact that another member of the family was admitted in the fall of 1956 as a post-graduate student at the Institute of Physics of the Academy of Sciences of Ukraine in Kiev, and she remained as a main support of the family with the one year old daughter on her hands. With the proper to her selflessness Yuliya Stanislavovna supported this hard turning in the family's life, understanding very well its perspective. In the opinion of the all members of the family, where the daughter Elena, the son Evgenii and the grandson Anton also became physicists, she was the mind, honor and conscience of our family, the founder of its most traditions. Her civic attitude and world outlook were formed under the influence of the russian, soviet and world literature. She liked very much to read and used any possibility to sit down with the book in the hands. The first ten-years period 1951-1961 after the graduation of the KSU played the role of the preparatory stage for the next, main period of her scientific activity. It began in 1961 simultaneously with the opening of the Academy of Sciences (ASM) of MSSR, now of Republic of Moldova. This fact once again underlined the enormous role played by the ASM in the life of our generation as well as of the following generations. The analogous role played by KSU was mentioned above. Both great events determine the scientific and cultural level of our country and are impossible to be over-estimated. The transfer of Yuliya Stanislavovna from KSU to ASM was motivated by her trends to concentrate on the scientific work, to study the physics of deformation on more deeper level taking into account the dislocations evolution, using the contemporary methods of electron microscopy, acoustical emission, cathode-luminescence and other methods. These investigations supplemented the well known X-ray crystallographical studies organized and headed in ASM by the academician T.I.Malinovskii and his collaborators. More so, the scientific group headed by Yuliya Stanislavovna was for the beginning incorporated in the frame of the laboratory headed by academician T.I.Malinovskii.

V.N. Rozhanskii, unknown, V.L.Indenbom, Yu.S. Boyarskaya, N.N.Kristofel,
A.A.Urusovskaya, Riga, 1962, the All Union Conference on the Physics of the
Alkali Halides Crystals.

Institute of Applied Physics (IAP) of the ASM.
IAP of ASM was organized in 1964 on the base of the physical laboratories of the former Institute of Physics and Mathematics (IPM) of ASM headed in 1961 by
academician V.A.Andrunakievich and of some laboratories of the Institute of
Electro-Physical Problems. The director of LAP ASM became the academician Boris Romanovich Lazarenko, Laureate of the State Prize in the field of Science and Technology of USSR, the founder, discoverer and inventor of the method of electron-spark processing of the materials. Soon this method became well known and widely used in the world. It was a happy event for our Institute to have such exceptional director with wide scientific interests, large russian soul in the best sense of the words and irreproachable honesty.

Yuliya Stanislavovna and her first collaborators M.I.Val'kovskaya, R.P.Zhitaru and D.Z.Grabko in the frame of LAP developed and used different methods of investigations such as the polarization-optical and interferometry methods and later scanning and transmission electron microscopy. The complexity of the studied phenomena are determined by the different contributions of the elasticity, plasticity and fragility of the materials. The main representatives of the plastic deformation are the linear defects of the crystalline lattice named as dislocations. They can be the edge and screw types and can form the accumulations and different structures under indentation processing. Side by side with them there are also the point lattice defects so as vacancies, interstitial atoms, impurities or their crowds and clusters. The dislocations can interact with them undergoing the scattering processes or even generate some lattice point defects. Another lattice distortions can be the kinks domains and disclinations. By these reasons there were needed all above mentioned methods as well as another ones. At the same time the intense and close collaboration with the central scientific centers of USSR was organized, whose leader collaborators visited this group in LAP taking part at the reports and discussions of the scientific results obtained here. The usefulness of such visits and discussions can not be over-estimated. Between them one can remember Professor V.N. Rozhanskii, Professor V.L.Indenbom, Professor A. A. Urusovskaya and Dr. G.V.Berezhshkova from the ICAS from Moscow, as well as Professor N.A. T'yapunina from Moscow State University, Professor V.R.Regel', Professor B. I. Smirnov, Professor A.I.Slutsker, and Professor O.V.Klyavin from the A. F. Ioffe Physics-Technical Institute of the AS of USSR in Leningrad, Professor R.I.Garber from the Khar'kov Physics-Technical Institute of the AS of Ukraine, Dr.O.A.Fedorenko from the Khar'kov Institute of Monocristals of ASU and other.
Less frequent but very important were the visits of the academicians of the AS of USSR A.M.Prokhorov, Yu.A. Osip'yan and V.L.Ginzburg in the frame of the sessions in departure of the Division of General Physics and Astronomy of the AS of USSR. Their influence as well as of Professor M.V. Klassen-Neklyudova from ICAS and professor M. P.Shaskol'skaya from the Moscow Institute of Steel and Alloys was decisive and fruitful and promoted the quick grow of the scientific collaborators. Due to the intensive and fruitful discussions Yuliya Stanislavovna succeeded to approbate many of the conceptions and models elaborate by her or to describe in more proper way the observed phenomena using the suggestions and advices of the guests.

Yu.S. Boyarskaya, 1966.

For example, in discussions with Professor R. I. Garber, it became clear the necessity to use the results concerning the distribution of the field of strengths around the axial force acting on the continuum elastic medium. This field of strengths is known as the Hertz model. The new idea appeared here was to introduce additionally in consideration the slip and of cleavage planes and to determine the projections of the strengths obtained in the Hertz model on the sliding and cleavage planes. On this way it became possible to understand while the dislocations, which appear under the action of indentor, modeled now as an axial force, are moving on the definite planes and in the definite directions rather than in another ones. On this way it becomes possible to understand the origin of the polar anisotropy of the indentation and of the scratches traced on the octahedral faces of the monocrystals NaCl, PbS, and CaF₂. These faces appear at the intersections of the planes perpendicular to the direction of the type <111> with the cube and have the surface symmetry group, which do not contain the operation of spatial inversion even if it is present in the cubic symmetry group. Another achievement is the concept of the reverse deformation, when the
pressure of indentor is directed inside the sample whereas the forced out material moves in opposite direction. On this base it was proposed the scheme of the material plastic flow in the process of indentation.

The model of the material plastic flow. Reverse deformation and polar anisotropy.
According to this model the active slip planes can be divided into two groups. For example, in the case of the model crystal NaCl one group consists from the divergent slip planes, forming the tetrahedral pyramids with the apex near the surface and with the base at the depth. The slip planes of the second group form the inverted pyramids. The former planes are responsible for the material shift to depth of the sample, whereas the latter ones for its transport to the surface and for the formation of the pile-ups around the indentation. The most important detail of the model is the existence, as wit as mentioned, of the reverse
plastic deformation. In difference from the elastic reverse deformation, the reverse plastic deformation is due to the motion and generation of the dislocations. The model is true for the various types of crystals deformed in the wide range of temperatures and has a general character.

First row, from left to right: M.S.Kats, Yu. S. Boyarskaya, V. M. Stepanova
(the guest of the laboratory) and P.Baraptarlo. Second row, from left to right. M.I. Val'kovskaya, D. Z. Grabko, V. Pavlyuk, R.P.Zhitaru and E.Purichi.

The experimental data and the theoretical calculations shown, that the quadratic slip lines are situated exactly in the places where the hills are formed. The electron microscopy investigations and the decoration technique permit to observe the dislocations under the surface of the sample. They confirmed the made conclusions. The proposed model can also explain qualitatively the experimental data concerning the length of the dislocation rosettes arms in dependence on the orientation of the sides of the indentor as regards to the crystallography directions. In all the cases it is necessary to calculate the tangential projections on the slip planes of the components of the stress tensors determined by the field of strains in the Hertz model. The polar anisotropy on the octahedral faces mention above was observed due to the formation of the three-arm rosettes with dislocation arms long in one directions and short in opposite ones. This fact was explained invoking the non-symmetrical orientation of the slip planes as regards the surface under indentation and by
corresponding calculations. As was earlier mention, an installation comprising a metallography microscope and a loading device was proposed, which permitted the observation of the indentation and its surrounding deformed region as well as the failure patterns under the load and after unloading. In these conditions the reverse or recovery elastic and plastic deformations were observed after the indentor removal. It was completely logic. But in 1992 unexpectedly a new unknown phenomenon was observed, and published in the paper by Yu.S. Boyarskaya, D.Z.Grabko and N.A.Lavrovskaya, Fiz.Tverd.Tela, 1992,v.34,p.2292 (1992).

New ideas: the impulse mechanism of plastic deformation, the prolonged plastic deformation and the pseudo-mobility of the dislocations.
They were described in some publications. One of them appeared post mortem and was written by Yu.S.Boyarskaya, R.P. Zhitaru, D.Z.Grabko and V.A. Rahvalov, the authors of the review paper published in the Journal of Material Science, vol. 33, pages 281-285, (1998). This description will be repeated below. An unusual fact was revealed for MgO crystal. It consists in the further development of the plastic deformation region near an indentation. It continues in the same direction as in the presence of indentor, but takes place after the indentor removal from the sample. The enhancement of the slip squares formed near the indentations take place during the unloading.

From left to right: L.I. Vasiliev, B.I. Smirnov, M.S.Kats, Inna (last name forgotten),
F, Lavrent'ev, R.P. Zhitaru, Manika Ilze, Yu.S. Boyarskaya,
Vadul lui Voda, river Dniester, 1986.

These slip lines are the traces of the slip planes, which are responsible for the material transport from under the indentor to the surface, as well as for the formation of the hills of the pressed out material..Thus the additional material transport to the surface occurs during the unloading process. The prolonged plastic deformation appeared. It can be explained by the new mechanism of microindentation suggested in 1985 in the paper by Yu.S.Boyarskaya, D.Z.Grabko and D.S. Pishkova. Cryst. Research and Technology, v.20, K113-K114 (1985). Side by side with the continuous mechanism of the indentation formation, another one named as impulse mechanism can exist. In accordance with the first mechanism the development of the indentation and of the dislocation structure around it, named as a dislocation rosette, take place simultaneously. In the case of impulse mechanism this synchronicity is violated, what can occur with the hard materials. For example if in the deformed region a crowd of dislocations could be accumulated, then the development of the dislocation structure could be stopped for some time. The removal of the load can act as a trigger mechanism, leading to the break through of the locally accumulated dislocations and to the relaxation of the locally accumulated strengths. In this case the new dislocation rosette arms will be formed, or the previous formed arms can be
prolonged without the essential change of the indentation. And all of them take place in the absence of the loading or during the unloading. In difference from the crystal MgO, on the crystals NaCl and LiF the essential changes of the dislocation structure after the unloading were not observed. The impulse mechanism of the dislocation rosette formation leads to new look on the determination of the dislocation mobility. In this case the motion of
dislocations take place in another conditions as compared with the continuous deformation. The mobility determined in the presence of the high local stresses may be named as pseudo-mobility. The non-correlated changes of the microhardness and of the dislocation mobility were observed at low temperatures. During the impulse mechanism the work effectuated by the external load can be directly transformed into the dislocation motions and into the dislocation rosette formation without the increasing of the indentation. Now some words concerning the thermodynamics of the microindentation and the acoustical emission during the cracks formation and annihilation in fragile materials will be added.

From left to right: daughter Elena, son Evgenii and Yuliya Stanislavovna,
about 1969.

Microindentation as a thermofluctuative process. The acoustical emission due to cracks formation.
In collaboration with Prof. V.R.Regel', with participation of the collaborator M.S. Kats, the kinetics of the process of microhardness was studied.especially in the frame of the A.F.Ioffe Physics-Technical Institute of the AS of USSR. It was established that the temperature of the sample plays an important role in determination of the velocity of penetration of the indentor into the material.
The experimentally revealed dependence is characteristic to the thermofluctuative processes with the activation energy linearly decreasing in dependence on the strength.
On the base of these fundamental investigations the new instrument to measure the thermofluctuative parameters of the samples was realized. It was included in the list of the most important implementations of the AS of USSR in 1977.
The fragility of the materials was investigated using the acoustical emission arising during the microindentation and sclerometry testing accompanied by the cracks formation and material destruction. The special equipment was elaborated.

V.A. Moskalenko, Yu.S. Boyarskaya, D.N. Zubarev and S.A. Moskalenko.
Kishinev, about 1985.

Formation of scientific school in the field of the physics of strength and plasticity.
All these results of fundamental investigations and their implementations were accompanied by the scientific grow of the investigators. To the period of time 1975-1976 Yuliya Stanislavovna became Doctor of Sciences (doctor habilitat now), whereas M.I.Val'kovskaya, R.P. Zhitaru, D.Z.Grabko and M.S.Kats defended their candidate (now doctor) dissertations in the physics-mathematical sciences. To this period of time one can also attribute the formation of the scientific school in the field of the physics of strength and plasticity. In the frame of the international specialization theses investigators were concentrated on the physics of the non-homogeneous strained state arising under micro-indentation processing. Later on S.S.Shutova, MA.Linte , M.Dyntu, D.S.Pishkova,
N.A.Palistrant became candidate (doctor) of phys.-math. sciences, whereas D.Z.Grabko and R.P.Zhitaru became Doctors of Sciences -doctor habilitat in physics-mathematical sciences. Some words concerning the defense by Yuliya Stanislavovna of her doctor of sciences thesis. In 1972 the publishing house "Shtiintsa" of the ASM published the monograph of Yuliya Stanislavovna "The deformation of the crystals under the micro-indentation processing", which soon became the table-book for the specialists in this field. On the base of the monograph the doctor of sciences thesis was written and successfully defended in 1974 at the Institute of Metallo-Physics of the AS of Ukraine in Kiev. As the
official opponents were invited academician of AS of USSR, vice-president of the AS of Ukraine V.I.Trefilov, Professor V.N.Rozhanskii and Professor M.P.Shaskol'skaya, whereas as the leading organization in this field was named the Kharkov Physics-Technical Institute of the AS of Ukraine, where Professor R.I.Garber headed a profile laboratory. Due to the reorganization of the Highest Attestation Commission of the Counsel of Ministries of USSR in this period of time the thesis was subjected to a supplementary examination at the Scientific Counsel of ICAS USSR in Moscow, where it was unanimously confirmed. This fact testified about the high scientific level of the presented dissertation. As in 1955 as well as 20 years later the main approbations of her scientific life
Yuliya Stanislavovna happened to pass in ICAS USSR. The considerable interval between two theses was conditioned by the requirement to leave to the following generations the incontestable scientific results. It is the main requirement obligatory for all responsible scientific collaborators with so high scientific degree. Another reasons were the difficulties to work in this field at the initial period of investigations, what was mentioned above.
There were other important events in the scientific life of Yuliya Stanislavovna after the described period of time. All of them were related with the next extension and deepening of the investigations. One of them was the Session in departure of the Scientific Counsel of AS of USSR on the problem "Physics of Strength and Plasticity" held ten years later, after the described above approbations. The Session was held in the surroundings of Kishinev in
Vadul-lui-Voda on the bank of the Dniester river in the fall of 1986. It was a recognition of the authority and significance of the investigations effectuated in IAP ASM. The session underlined that the method of micro-indentation is one of the most simple and informative to study the elasticity, plasticity, fragility and destruction of materials. It is applicable to small size samples, fragile and hard materials for which another methods are inapplicable. A number of new physical phenomena were revealed and were studied. Between them the polarity of plastic deformation of the material with different types of chemical bonds., the reverse plastic deformation, the mobility of the dislocations in the field of the non-homogeneous strains, the interstitial mechanism of the plastic deformation and other. The efficiency of the method is enlarged by the possibility to register the diagram of the load-penetration depth, by the determination of the resistance to cracks formation, using acoustical emission, by the measuring of the thermofluctuative parameters, and other. The methods of transmission and scanning electron microscopy as well of micro-cathodo-luminescence and decoration essentially enlarged the informativity of the microindentation method. All the main results obtained by the collaborators of the laboratory of the mechanical properties of crystals of the LAP of ASM organized and headed by Yuliya Stanislavovna were high appreciated.
The new results concerning the impulse mechanism of indentation, the prolonged deformation and the pseudo-mobility of dislocations were revealed at the end of this period and at the beginning of the next one. They essentially enlarged the understanding of the studied physical phenomena arising under the micro-indentation. The Scientific Counsel recommended to hold the regular sessions one time in 3-4 years on the base of the IAP ASM, of the ICAS USSR and of the Baikov Institute of Metallurgy of AS of USSR. The authority of IAP of ASM and of the scientific school in this field was recognized. Another recognition was the participation of Yuliya Stanislavovna as a member of the inter­governmental USSR-GDR Scientific Counsel on the Physics of Strength and Plasticity. In the frame of this collaboration Dr. Peter Grau from the Martin Luter University of Halle more ten years visited IAP ASM., being interested in the investigations of the fragility of crystals using the method of acoustical emission. Here one can remember the collaboration with academician of ASM B.T.Matienco in the frame of the Moldavian Society of Electron Spectroscopy organized and headed by him, with Professor V.A.Likhachyov from the Leningrad State University in the frame of the All Union Scientific Counsel, which gradually was transformed into the Center of collaboration in this field of the New Independent States of the Former Soviet Union. The common scientific interests leaded to a fruitful collaboration with Professor Yu.V.Milman, member-correspondent of NASU, head of laboratory in the Institute of Metallophysics of NASU in Kiev. His high appreciation of the knowledge accumulated in this field by the moldavian group of investigators he expressed once by comparing in jest Yuliya Stanislavovna with the queen of microhardness. If the queen was recognized, it means at the same time the recognition of the princesses, who formed the main staff of this laboratory in IAP ASM. The foundation of the scientific bases and the achieved understanding of the complicated processes taking place under the non-homogeneous deformation permitted to reveal and to begin the study of new interesting phenomena such as mentioned above impulse mechanism of deformation, prolonged deformation, pseudo-mobility of dislocations and other. These questions as well above mentioned main directions of investigations were in the center of attention of Yuliya Stanislavovna in the last ten years period of activity 1986-1996. Up till the fall of 1995 three theses of doctor habilitat in physics-mathematical sciences ( Doctors of Sciences) were defended by the Collaborators of the laboratory of mechanical properties of crystals of IAP ASM including professor Yu.S. Boyarskaya and principle scientific collaborators D.Z.Grabko and R.P.Zhitaru, as well as 9 theses of doctor (candidate) of physics-mathematical sciences namely M.I.Val'kovskaya, R.P.Zhitaru, D.Z.Grabko, M.S.Kats, S.S.Shutova, M.P.Dyntu, M.A.Linte,D.S.Pishkova. and N.A.Palistrant. The Laboratory of Mechanical Properties of Crystals of the LAP of ASM founded by Professor Yu.S.Boyarskaya was and remains as one of the outstanding scientific centre in this field recognized far from Moldova Nobody could imagine at the beginning of 1996, that so fruitful and dynamic activity of Yuliya Stanislavovna will break so unexpectedly in full swing. Utter devotion to the science, the intrinsic nobility and dignity, modesty and courage distinguished all her behavior and actions. She was kindly and well disposed as regards to the colleagues and collaborators, she liked very much the nature, animals and flowers, but it was possible to easy wound her. She endured the injustice of another people, herself being a correct person , who can not imagine another way of comportment. Yuliya Stanislavovna left her beloved science, the created scientific school, and laboratory, her colleagues, disciples and followers, being in the prime of creative life. The recollections were written by S.A. Moskalenko in collaboration with D.Z.Grabko and R.P.Zhitaru. 03.03.2003.