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Information × Registration Number 0216U001788, 0115U007124 , R & D reports Title The physical nature of ultra high-strength nanocrystals and technology of its realization in nanoscale needle-like crystals: manufacturing and attestation of tungsten and molybdenum samples popup.stage_title Head Mikhailovskij Igor Mikhailovich, Registration Date 19-04-2016 Organization National Science Center "Kharkiv Institute of Physics and Technology popup.description2 Report on Research Work: 50 p., 28 Figs., 60 References. The object of study is needle nanocrystals of tungsten and molybdenum. Purpose of study- project solves the basic problem of development of physical concepts on atomic mechanisms of obtaining the ultimate strength level in crystals and practical realization of superstrength states in nanosized needle-shaped specimens of Mo and W. Method of research - high resolution field ion microscopy and computer modeling. It was developed a methodology to produce nanoneedle samples of tungsten and molybdenum, and to perform their certification with atomic resolution in one technological cycle. Optimizing the parameters of high-field methods of manufacturing and surface treatment for the first time provided an opportunity for the manufacture of needle nanocrystals with perfect hemispherical and atomically smooth surface. The batch of nanoneedle Mo and W samples ranging in size from 10 to 200 nm was manufactured and certified for defects. The limit mechanical stresses in monocrystalline nanoobjects were determined during a high-field testing. The experimental strength of nanocrystals W nanocrystals are сorresponded to critical shear stress on the {211} and {110} planes along the <111> direction at the level of 10.0 ±2.0 and 9.1 ±2.0 GPа. It was shown that the upper stresses of needle-shaped W and Mo nanocrystals are independent of their diameter. The fracture of W and Mo nanocryatals aws accompanied by plastic deformation along the {211} и {110} planes. The strength of W bicrystals with grain boundaries of general type was of 14.4-20.2 GPa. This value is an order of magnitude higher than the strength of macrocrystals. The ideal cohesion strength of grain boundaries in Mo nanobicrystals with diameters of 25-80 nm is equal to 9.9 GPa at 77 К. The maximal strength in the nanometer range of diameters did not reveal the size dependence. That is evidence of the achievement of the ideal cohesive strength of grain boundaries. It was develop the physical foundations of production technology of nanoneedle probes and nanoemitters for modern microelectronics, high resolution field ion and scanning probe microscopy. Product Description popup.authors Дудка Оксана Валеріївна Ксенофонтов Вячеслав Олексійович Мазілова Тетяна Иванівна Михайловський Ігор Михайлович Саданов Євгеній Вікторович popup.nrat_date 2020-04-02 Close