Rapidly solidified Al87Ni7Cu3Nd3 amorphous alloy was prepared by using melt spinning. Its calorimetric behavior was characterized by using differential scanning calorimeter in a continuous or isothermal heating mode. phase transformation was investigated, with a special interest in primary crystallization, by using an in-situ examination of X-ray diffractometry (XRD) and high resolution transmission electron microscopy (HRTEM). The results show that, the whole devitrification of rapidly solidified Al87Ni7Cu3Nd3 amorphous alloy involves two main processes of primary crystallization and secondary crystallization that consist mainly of two reactions. For primary crystallization, the apparent activation energies, EIso and EKis and growth activation energies Eg are about 153, 166 and 288 kJ/mol, respectively. The interdiffusion of Al atoms is a rate-controlled step of formation of the α(Al) particles, but slow diffusion of Ni and Nd atoms plays a significant role in retarding growth of the α (Al) particles. For secondary crystallization, EIso, EKis and Eg of the first reaction are about 291, 208 and 290 kJ/mol, and those of the second reaction are about 367, 269 and 372 kJ/mol. The two reactions of secondary crystallization are controlled mainly in an interface-controlled three-dimensional mode, depending mainly on slow diffusion of Ni and Nd atoms.
High temperature plastic deformation behavior of non-orientated electrical steel was investigated by Gleeble 1500 thermo-mechanical simulator at strain rate of 0.01-10 s-1 and high temperature of 500-1 200 ℃. The stress level factor (α), stress exponent (n), structural factor (A) and activation energy (Q) of high temperature plastic deformation process of non-orientated electrical steel in different temperature ranges were calculated by the Arrhenius model. The results show that, with dynamic elevation of deformation temperature, phase transformation from α-Fe to γ-Fe takes place simultaneously during plastic deformation, dynamic recovery and dynamic recrystallization process, leading to an irregular change of the steady flow stress. For high temperature plastic deformation between 500 and 800 ℃, the calculated values of α, n, A, and Q are 0.039 0 MPa-1, 7.93, 1.9×1018 s-1, and 334.8 kJ/mol, respectively, and for high temperature plastic deformation between 1 050 and 1 200 ℃, the calculated values of α, n, A, and Q are 0.125 8 MPa-1, 5.29, 1.0×1028 s-1, and 769.9 kJ/mol, respectively.
