近片层γ-TiAl基合金宏观屈服的微观表征

THE MICRO CHARACTER OF THE MACROSCOPIC YIELD OF NEARLY LAMELLAR γ-TiAl BASED ALLOYS

将近片层-γTiAl基合金视为以等轴γ颗粒为基体,PST颗粒为夹杂的两相复合材料,基于细观力学自洽理论,对合金的有效弹性模量及基体和夹杂中的应力和应变场进行了解析分析计算,并结合细观力学的宏细观关联方法,确定了近片层-γTiAl基合金的宏观屈服的微观表征.结果表明:夹杂颗粒中的应力和应变场与外载及夹杂的体积分数f和椭球长细比ρ有关,软取向PST夹杂颗粒的微变形屈服导致近片层-γTiAl基合金材料的整体宏观屈服.

Nearly lamellar γ-TiAl based alloys have been considered as a composite material containing the PST particulates which have lamellar microstructures. The stresses and strains within the inclusions have been calculated and a micromechanical model has been proposed to predict the micro-yielding of the alloys. The results show that under applied stress, the macroscopic yielding of nearly lamellar γ-TiAl based alloys occurs at a stress level which can result in the micro-yielding of the soft-mode-oriented 45 or 50 deg PST grains in the alloy materials.