纳米Co_(78)Ni_(22)合金组织演变的原位高温X射线分析

In situ high temperature X-ray diffraction analysis of microstructure evolution of nanocrystalline Co_(78)Ni_(20) alloy

采用高温X射线原位分析法研究了喷射电沉积制备的晶粒尺寸5.1 nm的Co78Ni22合金连续加热及等温条件下组织转变。结果表明:在连续加热条件下,随着加热温度升高,晶粒尺寸经历由低温缓慢长大到中温异常长大再到高温正常长大过程,同时ε相向α相转变。在等温条件下,随等温时间的延长,ε相向α相转变且转变的温度降低,随等温温度的升高,这种转变加快,晶粒尺寸也会发生明显的长大。Co78Ni22合金加热过程中的异常晶粒长大与ε相向α相转变有关。

Microstructure evolution of nanocrystalline C%sNi22 alloy with grain size of 5.1 nm prepared by jet electrodeposition was studied by in situ high temperature X-ray diffraction during continues heating and isothermal processes. The results show that during continues heating process, the grain size grows slowly at low temperature, and then the unusual growth appears at middle temperature, afterwards, the grain size returns to normal growth at high temperature. Meanwhile, the e-phase transforms to ct-phase. During the isothermal processes, the temperature of transformation from e-phase to a-phase decreases with the increase of holding time, and the transformation from e-phase to a-phase accelerates with the increase of heating temperature, simultaneously, the grain size grows quickly. The unusual grain growth of the Co78 Ni22 alloy during heating processes is relation to the transformation from e-phase to u-phase.