(1. 中南大學(xué) 輕質(zhì)高強(qiáng)結(jié)構(gòu)材料重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083； 2. 中南大學(xué) 航空航天學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用機(jī)械球磨方法制備了含TiB2的γ-TiAl基合金粉末，并利用放電等離子燒結(jié)(SPS)技術(shù)制備了其合金粉末燒結(jié)體。結(jié)合X射線衍射(XRD)和掃描電子顯微鏡(SEM)分析方法對(duì)球磨合金粉末的形貌、相組成及其SPS燒結(jié)體的顯微組織結(jié)構(gòu)進(jìn)行觀察，分析其致密化及微觀組織演化過(guò)程，并利用萬(wàn)用拉伸試驗(yàn)機(jī)對(duì)燒結(jié)體的室溫力學(xué)性能進(jìn)行測(cè)試。結(jié)果表明：球磨處理后γ-TiAl基合金粉末呈現(xiàn)近球狀和不規(guī)則形狀粉末；粉末的相組成以α2相為主，同時(shí)含有一定量的γ相和少量的B2相。提高燒結(jié)溫度可促進(jìn)γ-TiAl基合金粉末SPS燒結(jié)致密化過(guò)程，適量的TiB2的添加也能夠有效降低合金粉末SPS快速致密化的起始溫度。當(dāng)TiB2添加量為0.2%(質(zhì)量分?jǐn)?shù))時(shí)，合金粉末在1100 ℃、40 MPa、10 min條件下燒結(jié)，其顯微組織呈現(xiàn)出由γ晶、α2晶和α2/γ片層結(jié)構(gòu)組成的混合組織結(jié)構(gòu)，各相分布均勻且晶粒細(xì)小，其所對(duì)應(yīng)的室溫抗拉強(qiáng)度也最高。
關(guān)鍵字: γ-TiAl基合金粉；TiB2；放電等離子燒結(jié)；顯微組織；力學(xué)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
