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Precipitation and recrystallization behavior during the continuous heat treatment of three beta-titanium alloys with various molydenum equivalents (VT22, Ti-15-3, and TIMETAL-LCB) was established. Following solution treatment, the materials were cold deformed to various reductions and then heated at rates between 0.17 and 50 K s Ϫ1 to peak temperatures below and above the beta-transus temperature. Precipitation below the transus was most rapid for the alloy with the least amount of beta stabilizing elements (VT22) and next fastest for the most-highly-alloyed material (TIMETAL-LCB), an effect ascribed to its large iron content. The reduction level was found to have a very strong influence on the uniformity of recrystallization and the recrystallized grain size. Because of the competition between precipitation and the temperature dependence of recrystallization nucleation and growth, the heatingrate dependence of the recrystallization temperature for the beta-titanium alloys was weak.

Abstract. It was shown very recently that despite high thermal stability some high entropy alloys, namely, intermetallic compounds of TiZrHfCoNiCu family, undergo martensitic transformation and exhibit shape memory effect [1]. It was also found that X-ray diffraction patterns taken from those compounds resemble qualitatively ones of B2 ordering type for austenitic state and B19` -for martensite. It is going to be shown [2] that the ordered structure of austenite phase is not B2 but is a result of group-subgroup transition down to triclinic P1 space group. Present paper reports onto the results of electron structure modelling combined with crystal structure analysis with the help of experimental data Rietveld refinement performed for TiZrHfCoNiCu intermetallics. Crystal structures of austenite and martensite phases for these high entropy intermetallics will be discussed.

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The atomic structure and mechanical properties of the carbyne (monatomic linear chains), containing from 2 to 21 carbon atoms, are theoretically investigated by ab-initio methods. We demonstrate the existence of a stable cumulene-structure in the inner part of chains with the number of atoms N>=10. We present a general stress-strain diagram of chains until the moment when they break, which enables to determine their strength, elasticity and fragility. For chains with N>=4, the relationship between the strength of the chain and the binding energy of the edge atom in the chain is established. The existence of scale-effect and "even-odd" effect for such properties as strength, elasticity and fragility is observed. We demonstrate that the 5-atom carbon chains show the maximum strength value.Comment: 8 pages, figure