纯钛(TA2)表面纳米化及其热稳定性研究

Study of Pure Titanium(TA2) Surface Nanocrystallization and Its Thermal Stablity

利用超音速微粒轰击(SFPB)技术对纯钛(TA2)试样进行了表面纳米化处理,并对SFPB处理后的试样进行不同温度的热处理。通过X射线衍射(XRD)、金相显微镜(OM)、显微硬度计和透射电子显微镜(TEM)分析测试,研究纯钛表面SFPB处理后的纳米化机理及其热稳定性。结果表明:经SFPB处理后试样表层形成了尺寸约为20nm随机取向的等轴晶粒,变形机制以孪生为主,且随层深增加,形变孪晶逐渐由多系转变为单系。纳米化后在450℃热处理时,纳米晶未发生明显粗化,因而具有良好的热稳定性。

Surface nanocrystallization treatment of pure titanium TA2 was conducted by Supersonic Fine Particles Bombarding（SFPB） followed by heat treatment at different temperatures.The nanocrystallization mechanism and the thermal stability of TA2 sample after SFPB treatment were investigated by optical microscope（OM）,X-ray diffraction（XRD）,microhardness testing and transmission electron microscope（TEM）.The results show that equiaxed nanocrystallites with random crystallographic orientations are obtained in the surface layer with SFPB,and the grain size is about 20 nm.During SFPB processing,deformation twinning is the main deformation mode in industrial pure titanium,and with the increase in the layer depth,twin deformation gradually changes from a multi-line system to a single one.In addition,when the annealing temperature is 450℃,the grain size is below 100 nm and the sample has good thermal stability;when the annealing temperature is higher than 450℃,the grains grow significantly（ 100 nm）.