Ti-8.15Si合金组织与性能研究

Study on Microstructure and Properties of Ti-8.15Si Alloy

摘要:

使用冷壁坩埚真空感应炉熔炼及金属模铸造方法，制备了Ti-8.15Si合金。利用光学显微镜、XRD、SEM、多功能试验机等技术，研究了合金的凝固组织特点、热处理对组织形貌的影响及抗压性能。结果表明，Ti-8.15Si合金可以获得αTi和Ti5Si3化合物形成的共晶组织，初生Ti5Si3相为比较粗大的棒状，共晶Ti5Si3相为细小的枝状或棒状，横断面呈六角形结构。1323 K保温60 min热处理使粗大棒状的Ti5Si3相显著减小；枝状Ti5Si3相变成非连续的、细小的粒状形态，改进了抗压综合性能。保温120 min Ti5Si3相逐渐长大，并且有少量块状的Ti3Si相生成，保温时间延长到180 min，Ti3Si相数量明显增多，材料的硬度和抗压强度增加，塑性降低。

Abstract:

Ti-8.15Si alloy was prepared by cold wall induction furnace melting and metal mould casting. The solidification structure characteristics, effects of annealing on the microstructure and the compressive property for the Ti-8.15Si alloy were investigated by OM, XRD, SEM and a multifunctional testing machine. Results show that the Ti-8.15Si alloy presents a eutectic structure composed of αTi and Ti5Si3 compound. The primary Ti5Si3 phases are coarse rod-like, while the eutectic Ti5Si3 phases are finer and dendritic or rod-like, and the cross section is hexagonal. After annealing at 1323 K for 60 min, the coarse rod-like Ti5Si3 phases become small obviously and the dendritic Ti5Si3 phases become discontinuous and fine grains, thus improving the compressive property. As for 120 min, Ti5Si3 grow gradually and a few bulk Ti3Si appears. As for 180 min, more Ti3Si phases are formed and the hardness and the compressive strength increase but the ductility decreases.