自蔓延燃烧合成多孔NiTi形状记忆合金的显微组织和孔隙结构

Microstructure and Pore Structure of Porous NiTi Shape Memory Alloys Prepared by Self-propagating High-temperature Synthesis

以镍粉和钛粉为原料，采用自蔓延燃烧合成技术制备了多孔NiTi形状记忆合金，研究了压坯压力、镍含量、钛粉粒径等参数对合金孔隙尺寸、孔隙均匀性和显微组织的影响。结果表明：自蔓延燃烧合成的NiTi合金为螺旋分层结构；压坯压力在100-200MPa范围内再经自蔓延燃烧合成的NiTi合金的孔隙均匀，且为三维连通结构，比较理想；镍质量分数为40％左右时，孔隙的分布和三维贯通性均较理想；当钛粉粒径较大时，出现了大量的液相和NiTi2、Ni3Ti等杂质相，反应很不充分，钛粉粒径在50-100μm之间为好。

Using nickel powders and titanium powders as raw materials, porous NiTi shape memory alloys （SMA） were prepared by using self-propagating high temperature synthesis （SHS） technique. The influences of parameters such as the sample pressure, nickel content and titanium powder size on pore size, pore uniformity and microstrueture were studied. The results show that the NiTi alloy synthesized by SHS technique had spiral and laminar structure. The samples pressed between 100-200 MPa had uniform pores and were ideal 3-D connection structure. With nickel mass fraction of 40% the pore distribution and three-dimensional interconneetability were ideal. When the granularity of titanium powers was large, liquid phase and impurity NiTi2, Ni3 Ti droplets turned up, and the granularity between 50-100 μm was preferable.