高温下镜面纯Fe的表面质量研究

研究了真空状态下保温60min不同退火温度对镜面纯铁的表面粗糙度、表面形貌及晶粒取向的影响。结果表明:在纯铁的多晶型性转变温度点以下,面均方根粗糙度随退火温度的升高而缓慢增大;在多晶型性转变温度及以上发生突变,从面均方根粗糙度为4~5nm的镜面突变到700nm;用扫描电子显微镜(SEM)观察样品表面,发现在810℃出现再结晶细小晶粒。研究了原材料及860~960℃之间几个温度点的X射线衍射{200}晶面极图,结果发现:晶粒在860℃开始择优取向,随温度升高,取向越来越明显;再结晶对表面粗糙度的影响不大,晶粒的择优取向使得晶粒在不同方向的膨胀系数不同,以及多晶型性转变导致体积的变化使得晶粒之间挤压造成晶粒之间的凹凸不平和表面较深较粗的晶界,这是造成粗糙度突变的主要原因。

Surface quality of mirror pure Fe at high temperature

This paper studied the effect of different annealing temperature on surface roughness, surface morphology and grain orientation of the mirror surface pure iron insulated for 60 min in vacuum. The results showed that the root mean square surface roughness increased slowly with increasing annealing temperature below the polymorphic transition temperature, and that root mean square surface roughness of mirror surface mutated from 4-5 nm to 700 nm in the polymorphic transformation temperature and above. Recrystallized fine grains were observed on the sample surface at 810 ℃ by scanning electron microscope (SEM). Research of XRD {200} crystal plane pole figures on the raw material and samples with several temperature points between 860-960 ℃ showed that preferential crystalline orientation had occurred at 860 ℃, and that the crystalline orientation is more and more obvious with the temperature increasing. The study found that the recrystallization has little effect on the surface roughness. Preferential crystalline orientation made different coefficient expansion in different directions, and the polymorphic transformation leads to volume changes causing uneven surface by the extrusion between crystal grains and the deeper grain boundaries, which is the main reason causing surface roughness mutation.