(福建农林大学 机电工程学院，福州 350002)
摘 要: 将近片层γ-TiAl基合金视为以等轴γ颗粒为夹杂、多孪晶PST单晶组分为微极基体的复合材料，运用微极理论研究与其等效弹性性能尺度效应对应的材料特征尺度lm和塑性流动行为尺度效应对应的材料特征尺度lp之间的关联。结果表明：相对于硬相的PST组分基体，软相等轴γ颗粒夹杂直径d与微极基体的材料内在的弹性特征尺度lm和塑性特征尺度lp相当时，夹杂尺寸将对合金材料的等效弹性模量和塑性流动行为产生一定的影响；合金材料的弹性模量随着夹杂颗粒尺寸的减小而增大，夹杂颗粒越小，合金材料的塑性流动硬化特征越明显。γ-TiAl基合金中与弹性性能尺度相对应的材料特征尺度lm与塑性行为尺度效应所对应的内在材料特征尺度lp相等，并与γ-Al合金复合材料基体组分中PST颗粒的尺寸大小一致。
关键字: γ-TiAl基合金；力学性能；微极理论；尺度效应
（College of Mechanics and Electrics Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China）
Abstract:The nearly lamellar γ-TiAl based alloy was considered to be a composite material that has lamellar polysynthetically twinned (PST) crystal grain matrix with equiaxed γ grain inclusion. The scale effect of effective elastic modulus and plastic flow behavior of the γ-TiAl based alloy was investigated using micropolar theory. The results show that the influence of the inclusion grains size on effective elastic modulus and macro plastic flow behavior of the alloy composite is distinguished when the inclusion particle size d is closed to the inherent elasticity and plasticity characteristics length (lm and lp) of the matrix material. With the decrease of size of inclusions embedded in a matrix, the effective elastic modulus of the material increases and its hardening property of the plastic flow is more significant. The intrinsic material characteristic length of elasticity and plasticity has the same value, which equals to the size of PST grains constituting micropolar composites matrix.
Key words: γ-TiAl based alloy; mechanical property; micropolar theory; scale effect
