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采用光学显微镜、扫描电镜和能谱分析仪考察了Cr、Mn、Zr、Ti、B的联合加入对AlZnMgCu合金的晶粒细化效果。结果发现在铸态合金中同时加入Cr-Mn-Ti-B时晶粒尺寸由256μm降为102μm。而当联合加入Ti-Zr-B后能产生更加强的细化效果,晶粒平均尺寸降为55μm。这是因为Cr、Mn原子簇团有利于促进Al3Ti形核并成为其结晶基底。当联合加入Cr、Mn、Zr、Ti、B时则可产生更加明显的晶粒细化效果,平均晶粒尺寸变为22μm。这是因为富Cr、Mn原子簇团在成为Al3Ti结晶核心后,部分Zr原子置换了其中的Ti原子形成了新的Al3(Tix,Zr1-x)结晶核心。而过渡族金属Cr、Mn还能降低液体金属和Al3Ti和Al3(Tix,Zr1-x)的表面张力,抑制结晶核心的长大。
The effects of Cr, Mn, Zr, Ti and B addition on the grain refinement of AlZnMgCu alloy were investigated by optical microscope, scanning electron microscopy and energy spectrum analyzer. As a result, it was found that the grain size decreased from 256 μm to 102 μm when Cr-Mn-Ti-B was simultaneously added to the as-cast alloy. However, when Ti-Zr-B was added in combination, a stronger refining effect was produced, and the average grain size was reduced to 55 μm. This is because the clusters of Cr and Mn atoms facilitate the nucleation of Al3Ti and become its crystalline base. When the joint addition of Cr, Mn, Zr, Ti, B can produce more obvious grain refinement effect, the average grain size becomes 22μm. This is because some Cr atoms and Mn atoms clusters become Al3Ti crystal nucleus, and part of Zr atoms displace Ti atoms to form a new Al3 (Tix, Zr1-x) crystal nucleus. The transition metal Cr, Mn can also reduce the liquid metal and Al3Ti and Al3 (Tix, Zr1-x) surface tension, inhibit the growth of the crystalline core.