| Abstrakt: |
Abstract: Analysis of elastic properties of Ti49Ni51(at %) and TiNi–TiFe single crystals, where the B2 phase can be both stable and unstable with respect to martensitic transformations, has been performed using the Every’s and Blackman’s diagrams, which are well known as two characterization methods of elastic properties of cubic crystals. Pair correlation relationships between (s2, s3), (s3, s1), and (F44, F12) have been calculated. The evolution of Cauchy pressure pChas been analyzed as a function of content of iron atoms in the crystalline lattice of the B2 phase of the alloys. It has been established that, irrespective of composition of the alloys, the Cauchy pressure is higher than zero and nearly monotonically decreases from 100.5 to 35.0 GPa with increase in content of Fe atoms in the crystalline lattice of the TiNi–TiFe B2 phase and increase in its stability with respect to martensitic transformations (up to complete stabilization). Such evolution of pCcorresponds to the data, according to which significant constituent of bond forces in TiNi is a metallic bond, and with increase in concentration of Fe atoms in the alloys instead of Ni atoms and approaching the composition of TiFe, the fraction of the covalent constituent of bond forces increases. |
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