(福建農(nóng)林大學(xué) 機(jī)電工程學(xué)院，福州 350002)
摘 要: 將近片層γ-TiAl基合金視為以等軸γ顆粒為夾雜、多孿晶PST單晶組分為微極基體的復(fù)合材料，運(yùn)用微極理論研究與其等效彈性性能尺度效應(yīng)對(duì)應(yīng)的材料特征尺度lm和塑性流動(dòng)行為尺度效應(yīng)對(duì)應(yīng)的材料特征尺度lp之間的關(guān)聯(lián)。結(jié)果表明：相對(duì)于硬相的PST組分基體，軟相等軸γ顆粒夾雜直徑d與微極基體的材料內(nèi)在的彈性特征尺度lm和塑性特征尺度lp相當(dāng)時(shí)，夾雜尺寸將對(duì)合金材料的等效彈性模量和塑性流動(dòng)行為產(chǎn)生一定的影響；合金材料的彈性模量隨著夾雜顆粒尺寸的減小而增大，夾雜顆粒越小，合金材料的塑性流動(dòng)硬化特征越明顯。γ-TiAl基合金中與彈性性能尺度相對(duì)應(yīng)的材料特征尺度lm與塑性行為尺度效應(yīng)所對(duì)應(yīng)的內(nèi)在材料特征尺度lp相等，并與γ-Al合金復(fù)合材料基體組分中PST顆粒的尺寸大小一致。
關(guān)鍵字: γ-TiAl基合金；力學(xué)性能；微極理論；尺度效應(yīng)
（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
