((上海交通大學(xué) 材料科學(xué)與工程學(xué)院，上海 200240))
摘 要: 采用基于密度函數(shù)理論的綴加平面波加局域軌道(APW+lo)方法和超晶胞方法對Nb含量為6.25%~37.5%Nb(摩爾分數(shù))的Ti-Nb二元合金的能量、電子結(jié)構(gòu)以及彈性性質(zhì)進行了理論計算，研究Nb含量對Ti-Nb合金的β結(jié)構(gòu)穩(wěn)定性和彈性性質(zhì)的影響。結(jié)果表明，隨著Nb含量的升高，Ti-Nb合金的β結(jié)構(gòu)穩(wěn)定性提高，正方剪切常數(shù)C′以及彈性模量K、E和G呈單調(diào)增加。當Nb含量為9.87%時，正方剪切常數(shù)大于并接近于零，此時Ti-Nb合金的β結(jié)構(gòu)穩(wěn)定性最低，并具有最低的彈性模量。
關(guān)鍵字: 鈦鈮合金；結(jié)構(gòu)穩(wěn)定性；彈性性質(zhì)；第一性原理
（(School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)）
Abstract:The energetic, electronic structure and elastic property of Ti-Nb binary alloys with Nb contents ranging from 6.25% to 37.5% (mole fraction) were calculated using the method of supercell and augmented plane waves plus local orbitals within generalized gradient approximation. Based on the calculated results, the influences of Nb content on the β phase stability and elastic property of Ti-Nb alloys were investigated. The results show that the β phase stability, tetragonal shear constant C′, bulk modulus, elastic modulus and shear modulus of Ti-Nb alloys increase monotonously with increasing Nb content. When the Nb content is 9.87%, the tetragonal shear constant C′ of Ti-Nb alloy reaches nearly zero from positive, and meanwhile the alloy achieves the lowest phase stability and the lowest elastic modulus.
Key words: Ti-Nb alloy; phase stability; elastic property; first-principles
