热作用对电铸镍/锆铜组织与结合强度的影响

Thermal Effects on Microstructure and Bonding Strength of Electroformed Nickel/Zirconium Copper

采用拉伸试验测量了电铸镍/锆铜高温下和经过热循环后的结合强度,利用扫描电子显微镜对断口表面形貌和经过高温或热循环后的试样组织进行观察。结果表明:经过高温后,电铸镍、电铸铜发生回复再结晶,晶粒由沿电铸方向的柱状晶转变为等轴晶,组织均匀化。电铸铜晶粒随温度升高长大。随着拉伸温度升高,电铸镍/锆铜结合强度下降,试样由穿晶断裂转变为沿晶断裂。经历最高温度在400℃及以下的热循环后,试样室温结合强度有小幅上升;经历最高温度在500℃及以上的热循环后,试样室温结合强度小幅下降。

The bonding strength of electroformed nickel/zirconium copper at high temperature or after thermal cycle was measured by tensile test.Fracture surface morphology and microstructure after high temperature or thermal cycle were observed by scanning electron microscope.Results show that recrystallization of electroformed nickel and electroformed copper occurs after high temperature preservation,and grains transform from columnar along the electroforming direction to equiaxed while the microstructure was homogenized.The grain size of electroformed copper grows rapidly as temperature increases.With the increase of tensile temperature,the bonding strength of electroformed nickel/zirconium copper decreases,and the transgranular fracture changes to intergranular one.The room temperature bonding strength after thermal cycleincreased slightly when the maximum temperature was below or equal to 400℃.Bonding strength decreased slightly when the maximum temperature was above or equal to 500℃.