拉应力作用下晶界位错运动过程的晶体相场模拟

Phase-field-crystal Simulation of Grain Boundary Dislocation Motion Under Tensile Stress

【目的】研究晶界位错在受到拉应变作用下的运动规律。【方法】采用晶体相场(Phase-field-crystal,PFC)方法研究拉应力作用下位错的动态演化过程,分析演化过程体系自由能。【结果】改变拉应力的施加方向,沿x轴施加拉应力时,位错运动呈现"左上右下"运动趋势,沿y轴施加拉应力时,位错运动呈现"左下右上"运动趋势。改变拉应力的施加方向对位错的运动及自由能曲线产生明显的影响。最终位错都运动到液相区,模拟区域成完整单晶。【结论】拉应变施加导致位错运动,体系能量上升,在方向不同的正应力的作用下,位错运动方式不同,体系原子之间跟随着外力场的作用作耦合运动,实现施加拉应变的物理效果。

【Objective】T h e m o t i o n l a w of the grain b o u n d a r y dislocation un d e r the action of thetensile strain is analyzed.【Methods】The p h a s e-field-crystal(P F C)m e t h o d is used to study thed y n a m i c evolution of the dislocation of the tensile stress,a n d the free e nergy of the evolutionprocess is analyzed b y using the continuous density field.[R e s u l t s l W h e n tensile stress is appliedalong the x axis,the dislocation m o v e m e n t trends to u p at the left a n d d o w n at the right.W h e ntensile stress is applied along the y axis?the dislocation m o v e m e n t appears to d o w n at the lefta n d u p at the right.C h a n g i n g the direction of applied tensile stress affects r e m a r k a b l y o n dislocationm o v e m e n t a n d free e nergy curve.Finally?all of the dislocation m o v e to liquid phase a n dthe simulation area b e c o m e s into a comp l e t e single crystal.【Conclusion】The tensile strain is a p pliedto cause the dislocation m o t i o n,t h e energyof the s y s t e m is increased,a n d the dislocationm o t i o n is different under the action of differentn o r m a l stress.W i t h the interaction b e t w e e n thea t o m s a n d the external force field?the physicaleffect of the tensile strain can be seen.