液体金属吸附促进位错发射的分子动力学研究

MOLECULAR DYNAMICS STUDY OF THE INFLUENCE OF LIQUID METAL ABSORPTION ON DISLOCATION EMISSION

用第一原理算出 Ｒｏｓｅ方程中的参量后，利用陈氏反演原理可以求出 Ａｌ－Ｇａ和 Ｃｕ－Ｇａ 的对势；从而可研究Ａｌ和Ｃｕ裂纹表面吸附液体金属Ｇａ之后对裂尖发射位错的影响． 结果表明，Ａｌ吸附Ｇａ后可使发射位借的临界应力强度因子从Ｋ_（Ｉｅ）＝０．５ＭＰａｍ^（１／２）降为 Ｋ_（Ｉｅ）＝０．４ＭＰａｍ^（１／２）；对Ｃｕ则从Ｋ_（Ｉｅ）＝０．５５ＭＰａｍ^（１／２）降为Ｋ_（Ｉｅ）（Ｌ）＝０．４５ＭＰｍ^（１／２），即 Ｇａ吸附后能促进位错的发射．另外，吸附 Ｇａ之后裂尖前方容易产生空位团及 Ｆｒａｎｋ位借。

The pair potential of Al-Ga and Cu-Ga have been calculated by Chen's reverse method with the parameters in Rose's equation and the first principle theory. The effect on dislocation emission from crack tip is studied when liquid metal Ga is adsorbed on the crack plane of metal Al or Cu. The results show that for Al the critical stress intensity for dislocation emission would decrease from K_(Ie)=0.5 MPam1/2 to K_(Ie)(L)=0.4 MPam^(1/2) due to the adsorption of Ga, and for Cu from K_(Ie)=0.55MPam_(1/2) to K_(Ie)(L)=0.45MPam^(1/2). It means that the adsorption of liquid metal would facilitate the dislocation emission. On the other hand, vacancy cluster and Frank dislocation would form easily ahead of the crack tip due to the adsorption of liquid Ga.