Micromechanical studies on effective moduli and microstructural sizeeffect forγ-TiAl-based alloys based on micropolar theory
-
摘要: 基于微极理论细观力学方法, 详细分析了近片层γ- TiAl 基合金材料有效弹性性能的微结构尺度效应。采用空间角度平均方法处理近片层γ- TiAl 基合金中横观各向同性PST( Polysynthetically twinned crystal) 颗粒夹杂的空间任意取向分布,并将Mori-Tanaka 法推广到微极介质, 建立了近片层γ-TiAl 基合金材料的有效弹性模量及其尺度效应的分析模型。结果表明: 当PST 夹杂颗粒直径尺度a 与微极基体材料(等轴γ颗粒) 的特征长度lm相当时, 合金材料的有效弹性模量的大小将受到夹杂PST 颗粒大小的影响, 夹杂颗粒尺度减小, 有效弹性模量增大; 而当PST 夹杂颗粒直径a 与微极基体材料的特征长度lm 相比很大时, 微极理论对有效弹性模量预测的结果将趋近于采用传统Cauchy 介质理论预测的结果。
-
关键词:
- γ- TiAl 基合金 /
- 有效弹性模量 /
- 尺度效应 /
- 微极理论 /
- 细观力学
Abstract: To investigate the size effect of effective elastic properties for a nearly lamellar γ- TiAl based alloy , amicromechanical method was developed based on the micropolar theory. The emphasis was placed on proposing ananalytical-micromechanical model. In cont rast to the classical micromechanics theory , the model was const ructed byusing the orientational average over all PST ( Polysynthetically twinned crystal ) grain orientations and extendingMori- Tanakaps method to micropolar mediums. The computed result s show that the size dependence is morepronounced when the PST particleps size a approaches the mat rix characteristic length lm , and with decreasing thediameter of PST particles , the effective elastic moduli of γ- TiAl based alloy increase. The classical prediction ofeffective elastic properties for Cauchy mediums is recovered when the PST particleps diameter tends to infinitycompared to the characteristic length of the micropolar mat rix.-
Key words:
- γ- TiAl based alloy /
- effective elastic moduli /
- size effect /
- micropolar theory /
- micromechanics
-
点击查看大图
计量
- 文章访问数: 1925
- PDF下载量: 791
- 被引次数: 0
下载:
