Ti₂Ni/TiNi微叠层复合材料的制备及表征

Using alternatively stacked Ti and Ni foils, a Ti₂Ni/TiNi micro-laminated composite was fabricated by hot pressed sintering at 900℃. The effect of diffusion time on the microstructure and constitutional phases of the composites was investigated. The scanning electron microscope (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were employed to analyze the microstructure, constitutional phases, phase structures and phase transition temperatures of the fabricated composites. The results indicate that Ti and Ni foils are gradually consumed with the increase of diffusion time and three intermetallic layers (Ti₂Ni, TiNi, Ni₃Ti) are produced at the interfaces of Ti/Ni. When Ni foils are completely consumed, Ti atoms diffuse into Ni₃Ti layers, transforming the Ni₃Ti layers into TiNi. After Ti foils are completely consumed, only alternatively arranged Ti₂Ni and TiNi layers exist. Moreover, there are lots of granular and strip-shaped Ti₂Ni phases distributing in the TiNi layers. The A_s, A_f, M_s, M_f and transition hysteresis temperature (ΔT) of the composite fabricated after 8 h diffusion are 75.9, 99.2, 63.6, 45.7 and 32.5℃, respectively.