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Here we report a transition in superelastic hysteresis loop from sharp with plateau to smooth without plateau for a Ni55−xCoxFe18Ga27 (x = 0-12) alloy system with increasing Co substituting for Ni up to 10 at.%. With the Co content reaching 10 at.%, the alloy exhibits the obvious characteristic of the strain glass transition, i.e., the frequency-dependent shift in temperature of the internal friction peak and frequency-dependent dip temperature, Tg, of the storage modulus following the Vogel-Fulcher relationship. The high-energy X-ray diffraction provides the direct evidence that the smooth hysteresis loops stem from a finite avalanche martensite transformation mode, inducing a long-range inhomogeneous stress field in the remained parent phase during deformation.

The influence of strain rate on development of deformation texture under a dynamic shock compression of a 904L stainless steel was quantitatively investigated using synchrotron X-ray diffraction and crystallographic orientation distribution function (ODF) analysis. The SplitHopkinson Pressure Bar (SHPB) technique was used to generate a high strain rate of >10 3 s À1 for preparing the deformed samples. Starting with an almost random texture in a solution treatment condition, the deformed material developed several typical texture components, such as Goss texture and Brass texture. Compared to the texture components displayed in the state of quasi-static compression deformation, it was found that the high-speed deformation generated much weaker texture components. In combination with the change in microstructures observed by electron backscattering diffraction (EBSD) and the transmission electron microscopy (TEM) technique, the high-energy X-ray diffraction provides a powerful tool for characterizing the strain-rate dependence of grain rotation at each stage of deformation. The deformation heterogeneity evident in our experiment can be explained by a transition of deformation mechanism from the dislocation/twin-dominated mode to a shear-band-dominated one with increasing strain rate.

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