Cr元素对Al-Ni合金凝固组织及显微硬度的影响

Effect of Cr on solidification structure and microhardness of Al-Ni alloy

采用光学显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)、X射线衍射分析(XRD)和硬度测试等手段研究Cr元素对Al-Ni合金的相组成、凝固组织及显微硬度的影响。结果表明,AlNi2.5Crx合金凝固组织主要为α(Al)相和共晶组织Al-Al_3Ni;Cr的添加细化了合金凝固组织,当Cr的原子分数为0.2%时,α(Al)细化效果最佳,当Cr的原子分数为0.3%时,Al_3Ni细化效果最佳;随着Cr含量的增加,合金硬度得到提高,当Cr的原子分数为0.5%时,合金硬度达到最大值51.2HV,这是固溶强化、细晶强化和晶格畸变共同作用的结果。

The effect of Cr on the phase composition,solidification structure and microhardness of AlNi alloys was studied by OM,SEM,EDS,XRD and hardness test.The results show that the phase composition of AlNi_（2.5）Cr_x alloys mainly includesα（Al）phase and Al-Al_3Ni eutectic.Solidification structures of the alloys are obviously refined by adding Cr.The average grain sizes ofα（Al）phase and Al_3Ni phase reach the minimum when Cr content is 0.2at.% and 0.3at.% respectively.With the increase of Cr content,the microhardness of the alloys rises.When Cr content is 0.5at.%,the alloy has the maximal microhardness of 51.2HV.This is mainly due to the combined action of solid solution strengthening,fine-grain strengthening and lattice distortion.