采用单轴拉伸对LY12粗晶材料进行超塑性研究 ,温度一定时 ,在较高和较低的应变速率下都得到了大延伸率 ,而处于中间应变速率的试样延伸率较低。SEM断口分析表明 ,晶界上产生的粘性物质对粗晶超塑性行为有决定性影响。在高应变速率下 ,晶界上粘性层很薄 ,被粘性层包围着的晶粒和亚结构在相互挤压和相对转动中容易细化 ,有利于超塑性变形能力的提高且不易产生孔洞 ,室温性能良好 ;低应变速率下 ,大多晶界上都有粘性物质包围且粘性层厚度增大 ,粘性物质的增多使超塑性变形能力增强 ,但易产生孔洞 ,使室温性能恶化 ;而中间应变速率区间 ,晶粒细化程度不够 ,晶界上未产生较多粘性物质 ,有少量孔洞产生且变形能力较差 The superplasticity of LY12 coarse-grained material was studied by uniaxial stretching. When the temperature is constant, the elongation of the LY12 coarse-grained material is both higher and lower, and the elongation of the specimen is lower at the intermediate strain rate. SEM fracture analysis shows that the viscous material produced on grain boundaries has a decisive influence on the superplastic behavior of coarse grains. At high strain rates, the adhesion layer on the grain boundary is very thin, and the grains and substructures surrounded by the adhesion layer are easily refined during mutual extrusion and relative rotation, which is beneficial to the improvement of the superplastic deformation capability and less prone to cavities. Room temperature performance is good. At low strain rate, the viscous material is surrounded by the majority of grain boundaries and the thickness of the adhesive layer is increased. The increase of viscous material enhances the superplastic deformation ability, but easy to produce holes to deteriorate the room temperature performance; while the intermediate strain rate Interval, the degree of grain refinement is not enough grain boundaries did not produce more viscous material, a small amount of holes produced and the deformation ability is poor