激光表面熔化对Ti-30Nb-4Sn合金晶体织构、显微组织、弹性模量和硬度的影响

Effects of laser surface melting on crystallographic texture, microstructure, elastic modulus and hardness of Ti-30Nb-4Sn alloy

骨科植入物的生物相容性与其弹性模量和表面性能密切相关。本研究的目的是阐明冷轧、再结晶和表面激光熔化(LSM)对双相(α″+β)Ti-30Nb-4Sn合金显微组织和力学性能的影响。对冷轧态基体进行X射线衍射织构分析(XRD)显示有[302]α″//ND织构成分,而对再结晶态基体的分析显示有[302]α″//ND和[110]α″//ND织构成分。XRD不能直接检测出β相织构,但是通过考虑α′′相和β相之间的位向关系可成功预测出[111]β||ND织构的存在。纳米压痕测试结果表明,冷轧态基体的弹性模量(63 GPa)低于再结晶态基体(74 GPa)。根据已有文献和本文研究结果,认为这种差异是由冷变形过程中晶体缺陷的引入造成的。纳米压痕/EBSD分析表明,纳米压痕结果不受晶体取向的影响。LSM对变形合金硬度、弹性模量和晶体织构产生的变化类似于再结晶热处理产生的变化,均在表面和基体之间产生刚度梯度。

The biocompatibility of orthopedic implants is closely related to their elastic modulus and surface properties.The objective of this study was to determine the effects of cold rolling,recrystallization and laser surface melting(LSM)on the microstructure and mechanical properties of a biphase(α″+β)Ti-30Nb-4Sn alloy.X-ray diffraction(XRD)texture analysis of the cold-rolled substrate revealed the[302]α″//ND texture component,while analysis of the recrystallized substrate showed the[302]α″//ND and[110]α″//ND components.Theβ-phase texture could not be directly measured by XRD,but the presence of the[111]β//ND texture component was successfully predicted by considering the orientation relationship between theα″andβphases.Nanoindentation measurements showed that the elastic modulus of the cold-rolled substrate(63GPa)was lower than that of the recrystallized substrate(74GPa).Based on the available literature and the results presented here,it is suggested that this difference is caused by the introduction of crystal defects during cold deformation.The combined nanoindentation/EBSD analysis showed that the nanoindentation results are not affected by crystal orientation.LSM of the deformed alloy produced changes in hardness,elastic modulus and crystallographic texture similar to those produced by recrystallization heat treatment,creating a stiffness gradient between surface and substrate.