NaCl造孔剂添加量对多孔NiTi合金孔结构和力学性能的影响

摘要

选用NaCl作为造孔剂，采用压制+烧结法制备孔结构和弹性模量可控的多孔NiTi形状记忆合金，采用SEM， XRD和形状回复率检测等测试手段研究造孔剂添加量对NiTi形状记忆合金的孔结构和力学性能的影响。结果表明：随NaCl添加量增加，多孔体孔隙率从39%上升到72%，孔径大于50μm的孔隙数量明显增加；多孔体主要由NiTi奥氏体相(B2)和马氏体相(B19′)组成，并存在少量NiTi2，Ni3Ti和Ni4Ti3等相；合金的弹性模量随造孔剂的添加从30%时的10.8 GPa下降到70%时的1.5 GPa；当添加量为50%时，多孔体孔隙分布均匀，大于50μm的孔隙占45%，弹性模量为4.8 GPa，形状回复率达到最高值83%，最适合多孔植入体的要求。%Porous NiTi shape memory alloy with controllable porosity and elastic modulus was prepared by press and sintering method using NaCl as space holder. The effect of space holder content on the pore structure and mechanical properties of porous NiTi shape memory alloy was studied by SEM, XRD and test of shape recovery rate. The results show that the porosity of the alloy increases from 39% to 72% with increasing space holder content. Moreover, the amount of large pores (diameter>50μm) increases significantly. The alloy is mainly composed of NiTi austenitic phase (B2) and martensite phase (B19′), and there also exists a small amount of NiTi2, Ni3Ti and Ni4Ti3 phases. The elastic modulus of NiTi alloy decreases from 10.8 to 1.5 GPa. The alloy fabricated with 50% space holder exhibits a homogeneous pore distribution, contains more than 45%of large pores (>50μm), and possesses elastic modulus of 4.8 GPa and highest shape recovery rate of 83%, which can meet the requirements of porous implants.