TC21钛合金稀土渗硼强化表面组织及性能

采用单体硼为供硼剂对TC21钛合金表面进行稀土催化表面强化热处理,对渗硼层组织形貌、硬度、磨痕形貌和磨损率进行了研究。结果表明单体硼渗剂中CeO2配比为7wt%左右的渗硼层连续致密,耐磨性较好;温度对于表层TiB2的厚度影响较大,提高温度可显著增大渗硼层厚度,随着保温时间的延长,表层TiB2层逐渐增厚并且更为连续,时间超过一定值后渗硼层厚度增加缓慢;渗硼层表层硬度随渗硼温度提高显著增大,随保温时间延长增加缓慢,渗硼温度在1 000℃时渗硼层近表层硬度可达3 200HV0.01左右,高硬度区域厚度可达20μm以上;TC21钛合金渗硼层表现出了良好的摩擦磨损性能,渗硼试样的比磨损率比未渗硼试样低50~60倍。

Microstructure and property of surface layer produce during rare earths solid-state boriding of TC21 titanium alloy

The rare earths (RE)-boronizing experiments are carried out for surface strengthening of TC21 titanium alloy. Microstructure, hardness, worn surfaces and specific wear rate of boride layers are studied. Results show that the boride layer with 7wt% content of CeO₂ in the agent is continuous and compact and it has better wear resistance. Boronizing temperature has a significant effect on the thickness of TiB₂ layer and the thickness of boride layer tends to significantly increase with it. As boronizing time goes on, the TiB₂ layer in surface becomes deeper and more continuous, whereas the thickness of boride layer increases slowly after a certain time. The microhardness of top layer is significantly increased by raising boronizing temperature, but it rises gently with time passing. At 1 000 ℃, the microhardness of top layer is about 3 200 HV_0.01 and the depth of high microhardness area is over 20 μm. The boride layer has a good wear resistance and specific wear rate of boride layers is 50-60 times lower than that of untreated specimen.