SPS烧结温度对NiTi/表面多孔Ti梯度合金组织和性能的影响

Effects of sintering temperatures on microstructure and properties of NiTi/surface porous Ti graded alloy by spark plasma sintering

利用放电等离子烧结技术制备NiTi/表面多孔Ti梯度合金,研究不同烧结温度对梯度合金微观组织、表面孔隙特征、力学性能及体外生物活性的影响及机理。结果表明:随着烧结温度的升高,梯度合金组织由NiTi、α-Ti、Ni、Ti2Ni、Ni3Ti混合相逐渐转变为单一NiTi和α-Ti相,内外层界面形成良好冶金结合,表面孔隙率和平均孔径呈缓慢减小趋势;同时抗压强度值快速增大而弹性模量值变化不大;1000℃制备的梯度合金不仅具有良好的表面孔隙特征(孔隙率35.8%、平均孔径423μm)、较高的抗压强度(632 MPa)、较低的弹性模量(9 GPa)及优异的超弹性行为(超弹性恢复应变>4%),而且体外生物活性显著提高。

NiTi/Surface porous Ti gradient alloys were prepared by spark plasma sintering(SPS) technology. The effects and mechanism of different sintering temperatures on the microstructure, surface pore characteristics, mechanical properties and in vitro biological activity of the gradient alloys were investigated. The results show that the gradient alloys are consisted of NiTi, α-Ti, Ni, Ti2Ni, Ni3Ti mixed phase and gradually transforms into NiTi and α-Ti phase with the increase of sintering temperatures. Furthermore, a stable metallurgical bonding on the internal and external interface of the alloys could be observed. Meanwhile, the porosity and average pore size of surface porous layer is in a slowly decreasing trend. As a result, the compressive strength of the alloys increases significantly, but the compressive elastic modulus of the alloys changes less. Gradient alloy sintered at 1000 ℃ not only exhibits good surface pore characteristics(35.8% porosity as well as 423 μm average pore size), higher compressive strength(632 MPa), lower the compressive elastic modulus(9 GPa) and excellent superelastic recovery strain(>4%), but also shows good in vitro biological activity.