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从实验和计算两个角度研究液体金属脆机理 .利用第一原理和陈难先三维晶格反演方法获得Al Ga和Ga Ga有效对势 .运用分子动力学研究液态金属吸附对位错发射的影响 .模拟结果表明 ,当Al晶体的裂纹表面吸附Ga原子之后 ,裂尖发射位错临界应力强度因子降低 .发射位错的临界应力强度因子从吸附前的 0 5MPa·m1/ 2降低为 0 .4MPa·m1/ 2 .吸附Ga原子导致临界应力强度因子降低的原因是吸附降低了裂纹的表面能 .同时 ,用自制的恒位移加载台 ,在透射电子显微镜 (TEM)中原位观察了 70 75铝合金吸附液体金属 (Hg + 3%Ga)后加载裂纹前方位错组态的变化以及脆性微裂纹的形核和扩展 .结果表明 :液体金属吸附后能促进位错的发射、增殖和运动 ;当吸附促进位错发射和运动达到临界状态时 ,脆性微裂纹就在原裂纹顶端或在无位错区中形核并解理扩展 .
The mechanism of liquid metal fragility is studied experimentally and computationally, and the effective counter-current of Ga and AlGa is obtained by the first principle and Chen Yan-xian 3D lattice inversion method.The influence of liquid metal adsorption on the dislocation emission is studied by molecular dynamics. The simulation results show that the critical stress intensity factor of the dislocated emission tip decreases when the Ga atom is adsorbed on the crack surface of the Al crystal.The critical stress intensity factor of the emission dislocation decreases from 0 5MPa · m1 / 2 before adsorption to 0.4MPa · m1 / 2. The reason for the decrease of the critical stress intensity factor is that the adsorption reduces the surface energy of the crack, and the adsorption of 70 75 aluminum alloy is observed by transmission electron microscopy (TEM) with a self-made constant displacement loading stage The change of dislocation configuration and the nucleation and propagation of brittle microcracks after liquid metal loading (Hg + 3% Ga) show that the liquid metal can promote the dislocation emission, propagation and movement after adsorbed liquid When dislocation emission and motion reach the critical state, the brittle microcracks nucleate and cleave at the tip of the original crack or in the dislocation-free zone.