Influence of low-temperature annealing on magnetic properties of (Nd_(0.625)Ni_(0.375))_(85)Al_(15) metallic glass

摘要

After a review of the selection process of (Nd_(0.625)Ni_(0.375))_(85)Al_(15) as a metallic glass with a relatively high glass-forming ability, we investigate the influences of its phase transitions by duplicating the heating process of the isochronal thermal analysis with low-temperature annealings. The structure, thermal stability and magnetic properties are characterized. And the influences on magnetic properties are particularly discussed with emphasis. Both the annealing processes, to the glass-transition temperature and to the onset temperature of crystallization, bring about a higher coercivity of the sample and a higher freezing temperature of the spin-glass-state. For the sample annealed to the onset temperature of crystallization, the influence is quite obvious and is ascribed to the formation of ferrimagnetic Nd_7Ni_3 phase, as detected by XRD. For the sample annealed to the glass-transition temperature, the indistinct influence is further identified with the analysis of the frequency dependence of the spin-glass-state, and it is mainly attributed to the change of the short-range order in the amorphous matrix.