Ti-8.15Si合金组织与性能研究

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。1323K保温60min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120minTi5Si3相逐渐长大,并且有少量块状的Ti3Si相生成,保温时间延长到180min,Ti3Si相数量明显增多,材料的硬度和抗压强度增加,塑性降低。

Study on Microstructure and Properties of Ti-8.15Si Alloy

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.