硼对医用Ti-22Nb-6Zr记忆合金的显微组织及性能的影响

Effect of Boron Addition on the Microstructure and Properties of Ti-22Nb-6Zr Shape Memory Alloys

摘要:

研究在Ti-22Nb-6Zr (at%) 合金中添加不同含量 (质量分数) (0.02%~1.5%)的硼元素，通过粉末烧结法成功制备了性能优良的含硼Ti-22Nb-6Zr记忆合金。结合OM、XRD、SEM分析发现，随着硼元素含量的增加，合金的β相基体中逐渐析出α相和TiB相，晶粒得到明显细化。通过压缩力学性能测试，发现硼元素对Ti-22Nb-6Zr合金的弹性模量和超弹性影响不大，但硼含量对其屈服强度和抗压强度有显著影响，当硼含量为0.02 %~0.1%和1%时，合金展现出较高的抗压强度（1450 MPa以上）和屈服强度（1250 MPa以上）。通过电化学测试，发现当硼含量在0.02%~1%时，合金具有较好的耐腐蚀性，腐蚀电流密度保持在10-6 A·cm-2以内。综合考虑合金的显微组织、力学性能与抗腐蚀性能，得出Ti-22Nb-6Zr记忆合金中适宜的硼添加量为0.02%~0.1%和1%

Abstract:

Ti-22Nb-6Zr (at%) shape memory alloys with various amount of boron (B) addition (0.02 wt%~1.5 wt%) were fabricated using a powder sintering method. Optical microscope, XRD and SEM were used to investigate the microstructure and phase constituents of the sintered alloys. It is shown that boron addition induces the precipitation of α phase and TiB phase in β matrix, which facilitates distinct refinement of microstructure. The addition of boron exerts only little influence on the Young’s modulus (around 30 GPa) and superelasticity (over 3%), but affects strongly the compression strength and yield strength of sintered Ti-22Nb-6Zr-B alloys. In order to acquire a relatively high yield strength and compression strength, the amount of boron addition into Ti-22Nb-6Zr shape memory alloys should be around 0.02 wt%~0.1 wt% and 1 wt%. Polarization curves analysis shows that the corrosion resistance of these Ti-22Nb-6Zr-B alloys is very good when boron content is about 0.02 wt%~1 wt%. Taking into account microstructure, mechanical properties and corrosion resistance, the appropriate amount of B addition for Ti-22Nb-6Zr shape memory alloys is 0.02 wt%~0.1 wt% and 1 wt%