Cr-Si合金钢表面纳米晶热稳定性的研究

Thermal Stability of Nanocrystallite in Surface Layer of Cr-Si Alloy Steel

采用超音速微粒轰击技术在Cr-Si合金钢的表面制备了纳米结构层。最表面层的晶粒尺寸约为16nm。利用X射线衍射(XRD)技术和透射电镜(TEM)分析技术对退火后表面纳米晶的结构变化进行分析。结果显示:当温度低于450℃进行退火时,表面纳米晶的尺寸变化不大。当退火温度达到450℃时,表面纳米晶失去稳定急剧长大到100nm左右。分析表明在低于450℃时,Cr-Si合金钢表面纳米晶具有良好的热稳定性,表面纳米晶的本征结构、退火时结构的动态回复以及渗碳体颗粒对晶界运动的阻碍是决定其具有一定的热稳定性的主要因素。

A nanocrystalline surface layer was fabricated on a chrome-silicon alloy steel using Supersonic Fine Particles Bombardment （SFPB）. The grain size of the top nanocrystalline layer was about 16 nm. The microstructural evolution of the top nanostructured layer after isothermal annealing was characterized by using X-Ray Diffraction （XRD） and Transmission Electron Microscopy （TEM）. Experimental evidence showed, as annealing temperature was lower than 450 ℃, a slight grain growth occurred in the top surface layer; as annealing temperature reached to 450 ℃, the grain grew sharply up to about 100nm due to loss of stabilization of the size. Experimental analysis indicated that the nanocrystallites in the surface layer of Cr-Si alloy steel was thermally stable under 450 ℃. The thermal stability of the nanocrystalline surface layer attributed to intrinsic structure, dynamic recovery of structure and cementite particles impending motion of grain-boundary during annealing treatment.