多晶材料的晶界应力分析

Analysis of Stress Near Grain Boundary in Polycrystalline Materials

许多有关多晶材料的研究表明:溶质原子偏聚到晶界上是引起材料性能变化的重要原因之一,而晶界张应力或压应力会引发溶质非平衡晶界偏聚或贫化。目前,材料内的宏观应力分析还不能准确描述晶界处的应力情况。本文建立了简化的奥氏体钢晶粒晶界模型,用有限元方法计算了拉伸载荷作用下材料微观结构上晶界处的应力情况。分析表明:(1)晶界与拉伸载荷方向的夹角发生改变时,晶界上应力分布情况也发生改变,晶界上最大拉应力可达到宏观拉伸应力的1.26倍;(2)随着晶界厚度增大,晶界上最大应力增大,最小应力减小。

Many studies on polycrystalline materials show that the segregation of solute atoms onto the grain boundaries is an important reason for the change of material properties, and the grain boundary tensile or compressive stress can cause the non-equilibrium segregation or dilution at grain boundaries. However, at present, macroscopic stress analysts of materials cannot accurately describe the situation of the grain boundary stress. A simplified grain-grain boundary model for austenitic steel was established, and the stress distribution at grain boundary under the external tensile load was calculated by the finite element method. Analysis results show that: (1) the stress distribution on grain boundary changes when the angle between grain boundary and external load changes, and the maximum tensile stress at grain boundary can reach 1.26 times of the macroscopic tensile stress. (2) As the thickness of grain boundary increases, the maximum stress at grain boundaries increases and the minimum stress decreases.