Deformation modes and ideal strengths of ternary layered Ti2AlC and Ti2AlN from first-principles calculations
Deformation and failure modes were studied for Ti2AlC and Tt2AlN by deforming the materials from elasticity to structural instability using the first-principles density functional calculations. We found (hat the TiC0.5/TiN0.5 slabs remain structurally stable under deformations, whereas the weak Ti-AI bonds accommodate deformation by softening and breaking at large strains. The structural stability of the ternary compound is determined by the strength of Ti-Al bond, which is demonstrated to be less resistive to shear deformation than to tension. The ideal stress-strain relationships of ternary compounds are presented and compared with those of the binary materials, TiC and TiN. respectively. For Ti2AlC and Ti2AlN. their ideal tensile strengths are comparable to those of the binary counterparts, while the ideal shear strengths yield much smaller values. Based on electronic structure analyses, (he low shear deformation resistance is well interpreted by the response of weak Ti-A) bonds to shear deformations. We propose that the low shear strengths of Ti2AlC and Ti2AlN originate from low slip resistance of Al atomic planes along the basal plane, and furthermore suggest that this is the mechanism for low hardness, damage tolerance, and intrinsic toughness of ternary layered carbides and nitrides.
Ting Liao Jingyang Wang Yanchun Zhou
Shenyang National Laboratory for Materials Science, institule of Metal Research, Chinese Academy of Shenyang National Laboratory for Materials Science, institule of Metal Research, Chinese Academy of Shenyang National Laboratory for Materials Science, institule of Metal Research, Chinese Academy of
国际会议
杭州
英文
161-167
2007-04-01（万方平台首次上网日期，不代表论文的发表时间）