Cu析出物对α-Fe辐照硬化贡献机理研究

The Contribution of Cu Precipitates to Hardening in α-Fe Matrix

采用分子动力学方法对α-Fe基中不同尺寸(直径0.5—2.5nm)共格Cu析出物和刃型位错12(111){110}的相互作用进行了研究,并深入探讨了不同温度(100—600K)和不同作用位置对析出物和位错相互作用的影响规律。结果表明,随着析出物尺寸的增加,位错受到的阻碍作用随之增大。该现象源于析出物尺寸增加导致位错通过时切割面积增大。同时温度的升高,降低了析出物对位错的阻碍作用,经对比发现1.0nm、1.5nm和2.0nm Cu析出物的临界剪切应力从100K升温至600K时平均降低了0.049Gb/L,而在100K、200K、300K、450K和600K环境下Cu析出物尺寸从1.0nm增至2.0nm时,临界剪切应力平均升高0.096Gb/L,说明析出物尺寸对位错运动阻碍作用的影响大于温度。位错在不同位置通过析出物时,发现从析出物中心通过时受到的阻碍作用最大,且当位错滑移面离析出物中心相等垂直距离时,位错从析出物上半部分通过时受到的阻碍作用均大于下半部分。这可能是由于位错滑移面下方的拉应力场和Cu析出物的压应力场相互作用贡献较大,导致位错运动受到了较大的阻碍作用。

The interactions between coherent Cu precipitates with different sizes(0.5-2.5 nm)and a 1 2(111){110}edge dislocation inα-Fe matrix have been investigated by molecular dynamics method(MD).Moreover,the impacts of temperatures(100-600 K)and different interaction positions for the interaction of precipitates and dislocations have been further explored.It is found that the increase of precipitates size enhances obstacle strength for dislocation glide.The reason is that the increase of precipitates diameter will increase the intercept area when dislocations pass through precipitates of different sizes.However,the rise of temperature causes the reducing of obstacle strength.By comparison,increasing precipitates diameters from 1.0 nm to 2.0 nm,critical shear stress of systems under different temperature rise by an average of 0.096 Gb/L.And when the temperature is increased from 100 K to 600 K,the critical shear stress of systems containing Cu precipitates with diameters of 1-2 nm reduces by an average of 0.049 Gb/L.The results qualitatively indicate that the effect of precipitates size plays a more important role in obstacle strength of precipitates for dislocation glide than temperature.When dislocation passes through precipitates at different sites,the precipitate whose center plane is on the dislocation glide plane is found to be the strongest obstacle.When the glide plane is the same vertically far away from the center plane of precipitates,the precipitates whose center planes are below the glide planes are stronger obstacles than those above the glide planes.The bigger contribution from the interaction between the tensile stress field below the dislocation glide plane and compressive stress field of Cu precipitate resultes in stronger hindrance for the dislocation movement.