(1. 中南大学 轻质高强结构材料重点实验室，长沙 410083； 2. 中南大学 航空航天学院，长沙 410083)
摘 要: 采用机械球磨方法制备了含TiB2的γ-TiAl基合金粉末，并利用放电等离子烧结(SPS)技术制备了其合金粉末烧结体。结合X射线衍射(XRD)和扫描电子显微镜(SEM)分析方法对球磨合金粉末的形貌、相组成及其SPS烧结体的显微组织结构进行观察，分析其致密化及微观组织演化过程，并利用万用拉伸试验机对烧结体的室温力学性能进行测试。结果表明：球磨处理后γ-TiAl基合金粉末呈现近球状和不规则形状粉末；粉末的相组成以α2相为主，同时含有一定量的γ相和少量的B2相。提高烧结温度可促进γ-TiAl基合金粉末SPS烧结致密化过程，适量的TiB2的添加也能够有效降低合金粉末SPS快速致密化的起始温度。当TiB2添加量为0.2%(质量分数)时，合金粉末在1100 ℃、40 MPa、10 min条件下烧结，其显微组织呈现出由γ晶、α2晶和α2/γ片层结构组成的混合组织结构，各相分布均匀且晶粒细小，其所对应的室温抗拉强度也最高。
关键字: γ-TiAl基合金粉；TiB2；放电等离子烧结；显微组织；力学性能
（1. National Key Laboratory of Science and Technology on High-Strength Lightweight Structural Materials, Central South University, Changsha 410083, China; 2. School of Aeronautics and Astronautics, Central South University, Changsha 410083, China）
Abstract:γ-TiAl based alloy powders containing TiB2 were prepared by mechanical ball milling method. The sintered alloys were fabricated by spark plasma sintering (SPS) technique. By combining X-ray diffractometry (XRD) and scanning electron microscopy (SEM), the morphology and phase constitution of as-milled alloy powders as well as the microstructures of SPS sintered alloys were observed. The densification process and microstructural evolution of the alloy powders during SPS were analyzed. The mechanical properties of the sintered alloys at room temperature were tested by a universal tensile tester. The results show that the as-milled γ-TiAl based alloy powders exhibit spherical-like shape and irregular shape. The phase composition of the powders consists of main α2 phase, a certain amount of γ phase and a few B2 phase. The SPS densification course of the γ-TiAl based alloy powders can be promoted by elevating the sintering temperature. The addition of TiB2 with a suitable amount to γ-TiAl based alloy powders can also effectively reduce the onset temperature of rapid densification. The microstructure of γ-TiAl based alloy powders with TiB2 addition of 0.2% (mass fraction) presents a mixed structure composed of γ grains, α2 grains and α2/γ lamellae when sintered at the condition of 1100 ℃, 40 MPa and 10 min. The phases are well-distributed and the grains are refined, leading to its higher tensile strength at room temperature.
Key words: γ-TiAl based alloy powders; TiB2; spark plasma sintering; densification; microstructure; mechanical property
