时效时间对表面机械研磨处理Cu-4.5Ti合金组织和硬度的影响

采用表面机械研磨法使Cu-4.5Ti合金表面形成纳米晶,利用X射线衍射分析,透射电子显微镜观察和显微硬度测量等手段研究时效时间对表面机械研磨处理Cu-4.5Ti合金组织和硬度的影响。结果表明:经过表面机械研磨处理后的Cu-4.5Ti合金发生了塑性变形,表层塑性变形明显,试样中出现了纳米晶结构,形成大量交割状态的机械孪晶;经过8 h时效处理后,试样中形成了更加致密的孪晶组织,并产生了更多孪晶区域。经表面机械研磨处理合金试样的显微硬度由表层向基体内部表现为先增大后减小的趋势,并最终达到稳定状态;经过8 h时效处理后试样到达峰值硬度,此时合金表层硬度增大至HV 213,并在离表层深度约50μm处获得HV 278的峰值硬度。

Effect of aging time on microstructure and hardness of Cu-4.5Ti alloys prepared by surface mechanical grinding

The nanocrystalline structure was present on the surface of Cu-4.5Ti alloys after the surface mechanical grinding treatment (SMGT). The effect of aging time on the microstructure and hardness of Cu-4.5Ti alloys was studied by the X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), and microhardness test. In the results, the Cu-4.5Ti alloys after SMGT show the plastic deformation, and the surface plastic deformation is the most obvious; the nanocrystalline structure is found in the alloy samples, and many mechanical twins are generated. After 8 h aging treatment, the denser twin structures are formed in the alloy samples, and more twins regions are present. The microhardness of the Cu-4.5Ti alloys after SMGT increases first and then decreases from outside to inside, and finally reaches a stable state. The alloy samples after 8 h aging treatment reach the peak hardness, which is HV 213 at the surface and HV 308 at about 50 μm off the surface.