摘要
采用微波烧结法成功制备多孔Ti-23%Nb(摩尔分数)形状记忆合金(SMAs)(不含造孔剂)。研究微波烧结对合金显微组织、相组成、相变温度、力学性能和形状记忆效应的影响。结果表明,烧结时间和温度对合金密度和孔隙度大小的影响较大,在900℃下烧结30 min的Ti-23%Nb SMA具有最小的孔径和最均匀的孔形状。多孔Ti-Nb SMA的显微组织主要含有针状和片状的α"、α和β相,且体积分数随烧结时间和温度不同而变化。由于β相稳定元素的含量较高,因此β相含量最多,而α和α"相的含量较少。900℃烧结30 min的样品呈现最优的极限强度和应变,而1200℃烧结30 min的样品则具有最高的超弹性。这些合金的弹性模量较低,可以避免"应力屏蔽"效应。因此,微波加热可以应用于烧结生物医用Ti合金并提高其力学性能。
Porous Ti-23%Nb(mole fraction)shape memory alloys(SMAs)were prepared successfully by microwave sintering with excellent outer finishing(without space holder).The effects of microwave-sintering on the microstructure,phase composition,phase-transformation temperature,mechanical properties and shape-memory effect were investigated.The results show that the density and size of porosity vary based on the sintering time and temperature,in which the smallest size and the most uniform pore shape are exhibited with Ti-23%Nb SMA after being sintered at 900°C for 30 min.The microstructure of porous Ti-Nb SMA consists of predominantα',α,andβphases in needle-like and plate-like morphologies,and their volume fractions vary based on the sintering time and temperature.Theβphase represents the largest phase due to the higher content ofβstabilizer element with little intensities ofαandα'phases.The highest ultimate strength and its strain are indicated for the sample sintered at 900°C for 30 min,while the best superelasticity is for the sample sintered at 1200°C for 30 min.The low-elastic modulus enables these alloys to avoid the problem of“stress shielding”.Therefore,microwave heating can be employed to sinter Ti-alloys for biomedical applications and improve the mechanical properties of these alloys.
基金
the financial support under the University Research Grant No. Q.J130000.3024. 00M57
