Y参杂对真空热压烧结TiAl基合金显微组织和力学性能的影响

Effect of Y doping and vacuum hot-press sintering on the microstructure and mechanical properties of TiAl-based alloys

摘要:

Ti-45Al (at %)和Ti-45Al-0.3Y (at %)样品通过真空热压烧结的方法制备。样品通过x射线衍射(XRD)、光学显微镜(OM)、背散射电子(BSE)以及压缩和硬度测试来研究Y参杂和热压工艺参数对TIAl基合金的显微组织和力学性能的影响。最优烧结参数为压力42MPa，在1400℃下保温保压90分钟。在此参数下，得到了组织均匀、晶粒细小的由γ相和γ+α2片层结构组成的双态组织。在热压温度1400℃,保温时间240分钟下,反应能完全达到，但会出现晶粒粗大现象。Y的加入对细化晶粒和片层间距有明显的作用，这有助于提高合金的机械强度。

关键词:真空热压烧结、Y参杂、显微组织、力学性能

Abstract:

Ti-45Al (at %) and Ti-45Al-0.3Y (at %) samples were fabricated by vacuum hot-press sintering (VHPS). The influence of Y additions and VHPS process parameters on the microstructure and mechanical properties of TiAl-based alloys were analyzed using x-ray diffraction (XRD), optical microscopy (OM), back-scattered electron (BSE) imaging, compression and hardness testing. Optimized sintering parameters were 42 MPa at 1400℃ with holding time of 90 minutes. Samples prepared under these conditions had uniform and fine grains with a duplex microstructure which consisted of γ phase and γ+α2 lamellar colonies. The reaction between γ-TiAl and α2-Ti3Al reached completion at a hot-press temperature of 1400℃ and holding time of 240 minutes. Unfortunately, significant grain growth occurred under these conditions. The addition of Y had an obvious effect on grain and interlamellar spacing refinement contributing to an increased mechanical strength of the alloy.

Key words:Vacuum hot pressing; Y doping; Microstructure; Mechanical properties