Temperature dependences of the flow and critical shear stresses of dispersion-hardening alloys

A study was made of the temperature dependences of the flow stress _0.1 (T) and of the critical shear stress _cr(T) of Cu-15% A1-(1–2)% Co, Cu-8% A1-(2–2.8)% Co, and Cu-4% A1–2% Co alloys containing noncoherent intermetallic particles. In the case of single crystals at temperatures 77–673° K there was a good agreement between the theoretically calculated values of the Orowan hardening and those found experimentally, so that the dependence _cr(T) was governed by the temperature dependence of the shear modulus G(T). For polycrystalline samples the usual dependence of the mechanical propertiesties on the grain size was not observed. At temperatures from 77 to 473–573°K the dependence _0.1 (T) was similar to the dependence G(T) and a good agreement was observed between the theoretically calculated dispersion hardening effects with those found experimentally. At temperatures T > 473–573°K the deformation was influenced greatly by grain-boundary glide, which enhanced the dependence _0.1 (T) compared with that expected theoretically.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 85–91, June, 1980.     

Special Features of Thermal and Stress Hysteresis of B2–R–B19' Martensitic Transformations in Aged [001]-Oriented Ti–50.6 at.% Ni Single Crystals

Russian Physics Journal - Stress-induced and thermal-induced martensitic transformations (MTs) in compression were investigated in [001]-oriented Ti–50.6 at.% Ni single crystals aged at 573 K...     

Shape memory behavior in Fe3Al-modeling and experiments

The Fe₃Al alloy with D0₃ structure exhibits large recoverable strains due to reversible slips. Tension and compression experiments were conducted on single crystals of Fe₃Al, and the onset of slip in forward and reverse directions were obtained utilizing high-resolution digital image correlation technique. The back stress provides the driving force for reversal of deformation upon unloading, resulting in a superelastic phenomenon as in shape memory alloys. Using density functional theory simulations, we obtain the energy barriers (GSFE – generalized stacking fault energy) for {1?1?0}〈1?1?1〉 and {1?1?2}〈1?1?1〉 slips in D0₃ Fe₃Al and the elastic moduli tensor, and undertake anisotropic continuum calculations to obtain the back stress and the frictional stress responsible for reversible slip. We compare the theoretically obtained slip stress magnitudes (friction and back stress) with the experimental measurements disclosing excellent agreement.