A first-principles study of site occupancy and interfacial energetics of an H-doped TiAl-Ti_3 Al alloy  

作　　者：WEI Ye ZHANG Ying LU GuangHong XU HuiBin 

机构地区：[1]School of Materials Science and Engineering,Beihang University,Beijing 100191,China [2]Deparment of Physics,Beihang University,Beijing 100191,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2012年第2期228-234,共7页中国科学：物理学、力学、天文学（英文版）

摘　　要：We investigate the site occupancy and the interfacial energetics of TiAl-Ti3Al binary-phase system with H using a first-principles method. H energetically prefers to occupy the Ti-rich octahedral interstitial site because H prefers to bond with Ti rather than with Al. The occupancy tendency of H in the binary phase TiAl-Ti3Al alloy from high to low is α2-Ti3Al to γ/α2 interface and 7-TiAl, because the decrease of the Ti local concentration is in the same order. We demonstrate that H can largely affect the mechanical properties of the TiAl-Ti3Al system. On the one hand, H at the interface reduces the interface energy with the H2 molecule as a reference, implying the TiAl/Ti3Al interface is stabilized. On the other hand, the ratio between the cleavage energy and the unstable stacking fault energy decreases after H-doping, indicating H will reduce the ductility of the TiAl/Ti3Al interface. Consequently, the mechanical property variation of TiA1 alloy due to the presence of H not only depends on the amount of TiAl/Ti3Al interfaces but also is related to the H concentration in the alloy.We investigate the site occupancy and the interfacial energetics of TiAl-Ti 3 Al binary-phase system with H using a first-principles method.H energetically prefers to occupy the Ti-rich octahedral interstitial site because H prefers to bond with Ti rather than with Al.The occupancy tendency of H in the binary phase TiAl-Ti 3 Al alloy from high to low is 2-Ti 3 Al to/2 interface and-TiAl,because the decrease of the Ti local concentration is in the same order.We demonstrate that H can largely affect the mechanical properties of the TiAl-Ti 3 Al system.On the one hand,H at the interface reduces the interface energy with the H 2 molecule as a reference,implying the TiAl/Ti 3 Al interface is stabilized.On the other hand,the ratio between the cleavage energy and the unstable stacking fault energy decreases after H-doping,indicating H will reduce the ductility of the TiAl/Ti 3 Al interface.Consequently,the mechanical property variation of TiAl alloy due to the presence of H not only depends on the amount of TiAl/Ti 3 Al interfaces but also is related to the H concentration in the alloy.

关 键 词：TiAI alloy hydrogen site occupancy shear deformation interfacial energetics FIRST-PRINCIPLES mechanical property 

分 类 号：TG146.2[一般工业技术—材料科学与工程] O484.1[金属学及工艺—金属材料]