( 1. 福建農(nóng)林大學(xué) 機(jī)電工程系， 福州 350002;
2. 北京理工大學(xué) 應(yīng)用力學(xué)系， 北京 100081)
摘 要: 基于γ-基多孿晶晶體微結(jié)構(gòu)及滑移系和形變孿晶空間晶體學(xué)位向分布的變形機(jī)制，提出了分析晶體屈服應(yīng)力對(duì)外載軸和片層界面夾角間的依賴關(guān)系及影響因素的細(xì)觀力學(xué)解析模型。 分析了α2相中柱面和錐面上滑移系的啟動(dòng)對(duì)多孿晶晶體屈服應(yīng)力的影響。模擬計(jì)算和分析結(jié)果表明： 當(dāng)θ=0°時(shí)， 位錯(cuò)滑移方向跨越片層界面， α2相中柱面滑移系開動(dòng)； 當(dāng)θ=45°時(shí)， 滑移方向平行片層界面；當(dāng)θ=90°方向時(shí), γ相中與片層界面斜交的孿晶開動(dòng)，而α2相中錐面滑移系由于其臨界剪切應(yīng)力(CRSS)很大而并不開動(dòng)。多孿晶晶體中孿晶與普通位錯(cuò)、 柱面與孿晶及錐面與柱面之間的CRSS比值關(guān)系可確定為k∶e∶z=1∶3∶18。
關(guān)鍵字: γ-基合金； 多孿晶晶體； 滑移系； 屈服應(yīng)力； 細(xì)觀力學(xué)
（ 1. Department of Mechanics-electrics Engineering,
Fujian Agriculture and Forestry University, Fuzhou 350002, China;
2. Department of Applied Mechanics,
Beijing Institute of Technology, Beijing 100081, China）
Abstract: An analytical micromechanical method, based on the lamellar microstructure, dislocation slip and twinning deformation mechanisms of polysynthetically twinned crystal (PST), was proposed to investigate the yielding stress change as function of loading angle(θ) between the load axis and the lamellar boundaries and some influence paramelers for a PST crystal. The effects of prism and pyramidal slip systems in α2 lamellars on the yield stress of polysynthetically twin crystals of TiAl were analyzed. The simulation and analyses results indicate that, when θ=0°, the slip is activited to cross the lamellar boundaries and the prism systems in α2 phase are activited. When θ=45°, the slip occurs parallel to interlamellar boundaries. When θ=90°, the twinning in γ phase are actived to cross the lamellar boundaries and the pyramidal slip systems in α2 phase are not actived due to much higher critical resolved shear stress on the pyramidal planes. The rate of critical shear stress (CRSS) for twinning to ordinary slip, prism to twinning and pyramidal to prism can be described as k∶e∶z=1∶3∶18.
Key words: γ-alloys； polysynthetically twinning crystal； slip system； yield stress； micromechanics
