固态渗碳对Ti-6Al-4V合金及其复合材料（TiB+La2O3）/Ti-6Al-4V表面显微组织和硬度的影响

摘要

以Ti−6Al−4V合金和(TiB+La2O3)/Ti−6Al−4V 复合材料为研究对象，研究固态渗碳法对两种材料表面显微组织和硬度的影响规律。将包覆于石墨粉中的试样置于密封的石英管中，在1227 K下保温24 h，成功实现了两种材料表面渗碳处理。显微组织和物相分析结果表明，固态渗碳后基体中原位生成了TiC 增强体和Ti−C 固溶体，且扩散层中的等轴α-Ti 相的体积分数随试样深度增加呈明显降低趋势；硬度测试结果表明，两种材料渗碳表面的显微硬度与未处理材料相比都明显提高了约100%，随试样深度增加而变化的碳含量在渗碳试样中形成了约300μm 的硬化层。同时，固态渗碳对内部组织和硬度的影响很小，表明该方法是一种有效强化钛合金及其复合材料的表面处理方法。%Solid carburization was employed to improve the hardness of Ti−6Al−4V alloy and (TiB+La2O3)/Ti composite. The samples wrapped in graphite powder were placed in sealed quartz tubes, followed by solid carburization at 1227 K for 24 h. Microstructure and phase analysis indicated that TiC reinforcements and Ti−C solid solutions were introduced after solid carburization. Moreover, the volume fraction of equiaxedα-Ti phase in diffusion layer decreased obviously with increasing sample depth. Hardness testing results indicated that both the carburized surfaces performed significant improvement of about 100% in micro-hardness compared with untreated materials. The variation of carbon contents with increasing sample depth resulted in a hardened layer of 300 μm in the carburized samples. Meanwhile, slight influence on the internal microstructure and hardness indicated that solid carburization was an effective method in strengthening the surface of titanium alloy and titanium matrix composite.