Search

The effects of Fe doping on the microstructure, martensite transformation and superelasticity in melt-extracted Ni50Mn25Ga25−xFex (x=1–6) microwires were investigated. The unique solidification process during melt-extraction creates the micron-sized diameter wires with small grains and semicircular cross-section. At ambient temperature Ni50Mn25Ga25−xFex (x 5 are martensitic phases with seven-layered modulated (7M) structure. The results point out that martensite transformation temperatures are strongly related to Fe content due to the change of valence electron concentration (e/a). Reversible superelastic strains of 0.92% and 0.75% are obtained in Ni50Mn25Ga21Fe4 and Ni50Mn25Ga20Fe5 microwires, respectively. It is demonstrated that the temperature dependence of stress-induced martensite (SIM) stress follows the Clausius–Clapeyron relation. The temperature dependence of SIM stress in Fe-doped Ni–Mn–Ga microwires is 10.5 MPa/K.

The phase evolution in the transition region of a bulk Zr56.6Cu17.3Ni12.5Al9.6Ti4 amorphous alloy wedge-ingot upon annealing has been studied. The result shows that the primary crystallized metastable phase and the amorphous matrix were found to crystallize into different products. Concerning the solidification process, it is deduced that the understanding of the competitive relationships among the intermetallic phases and the amorphous phase can be described by the phase analyses of solidification, rather than the widespread investigations of the crystallization by annealing.

This paper presents a new way of designing bulk metallic glasses in Cu–Ti–Zr–Ni system based upon binary deep eutectic. By conventional copper mold casting method, these alloys can be quenched into single amorphous structure with the diameter ranging from 3 to 5 mm. Experimental results show that among the alloy series designed Cu 52.55 Ti 30.05 Zr 11.4 Ni 6 and Cu 53.1 Ti 31.4 Zr 9.5 Ni 6 possess the relatively higher T rg of 0.603 and 0.598, respectively, which contribute to their good glass forming ability, and Cu 52.55 Ti 30.05 Zr 11.4 Ni 6 exhibits a relatively higher T g (694 K) and Δ T x (52 K), which indicate its good thermal stability.