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为了决定晶界位错在超塑性变形中的作用,用透射电子显微术研究了一种微细晶粒的超硬铝合金在超塑性变形前后的晶界位错组织。所得结果表明,在超塑性变形过程中,点阵位错与晶界间的交互作用导致非固有晶界位错的形成,而运动中的晶界位错与晶粒间的沉淀相微粒或三叉晶界间的交互作用则导致晶界位错塞积群的形成。这种塞积群中的晶界位错在超塑性变形过程中能以滑移-攀移方式沿晶界运动,其滑移分量导致晶界滑动,其攀移分量导致扩散通量而引起扩散蠕变,可协调晶界滑动产生的应变。根据上述结果,一种基于晶界位错运动的超塑性变形模型已被提出。在445°至505℃的温度范围内,晶粒尺寸为8.2和11.5μm的LC4超硬铝合金根据该模型计算得的超塑性变形的应变速率与实测数据符合得颇好。
In order to determine the effect of grain boundary dislocation in superplastic deformation, the grain boundary dislocation microstructure of a fine grain superhard alloy before and after superplastic deformation was studied by transmission electron microscopy. The results show that during the superplastic deformation, the interaction between lattice dislocations and grain boundaries leads to the formation of non-intrinsic grain boundary dislocations, while the movement of grain boundary dislocations and the intergranular precipitate particles or trigeminal Interaction between the grain boundaries leads to the formation of grain boundary dislocations. The grain boundary dislocation in this plugging group can move along the grain boundary in a slip-climbing manner during the superplastic deformation. The slip component causes the grain boundary to slide, and the climbing component causes the diffusion flux to cause diffusion Creep, can coordinate the strain caused by grain boundary sliding. Based on the above results, a superplastic deformation model based on grain boundary dislocation motion has been proposed. In the temperature range of 445 ° C to 505 ° C, the strain rate of superplastic deformation of the LC4 super-hard aluminum alloy with grain sizes of 8.2 and 11.5 μm was in good agreement with the measured data.