제1원리 계산을 이용한 Ti2AlC, Ti2AlN의 기계적 강도 및 방향별 인장특성 연구

Abstract

We investigated the elastic and mechanical properties of Ti2AlC and Ti2AlN MAXphase using first principles assessments. Particularly, we focused on effects of carbon andnitrogen vacancies. To elucidate the effect, we obtained not only elastic and mechanicalproperties of perfect Ti2AlC and Ti2AlN phases but also the vacancy contained models. Theelastic properties of Ti2AlN showed higher values than that of the Ti2AlC mainly due to relativelystable electronic bond formed between titanium and nitrogen atoms. In addition,carbon and nitrogen affected M-X covalent bond as well as M-A metallic bond. The carbonand nitrogen vacancies increased lattice parameters in normal to M-X plane direction. Incontrast, lattice parameter in M-X plane direction was decreased. This implied that thevacancies influenced both M-X and M-A bonds. As a result, the elastic and mechanicalproperties were varied, and (100), (010) shear plane elastic anisotropy was increased withformation of carbon and nitrogen vacancy.