微量元素Cr对ZL101合金微观组织和力学性能的影响

Effect of Trace Element Chromium on Microstructure and Mechanical Properties in ZL101 Alloy

采用真空电磁感应熔炼炉制备了ZL101-x Cr(x=0,0.1,0.2,0.3,0.5,0.8,质量分数,%)铝合金。利用OM、XRD、SEM、EDS及TEM等测试方法,表征了不同Cr含量实验合金微观组织,并测试其力学性能。结果表明:实验合金主要物相包括初晶α-Al、(α-Al+Si)共晶、Al_(13)Cr_(4)Si_(4)、β-Al_(12)(Cr,Fe)_(3)Si_(2)、富Fe相(β-Al5Fe Si和π-Al Si Mg Fe)。添加微量元素Cr后的实验合金组织均得到细化,随着Cr含量的增加,α-Al树枝晶趋于等轴晶转变,共晶组织区域变窄,富Fe相和共晶Si尺寸变小,在合金共晶组织中形成了Al_(13)Cr_(4)Si_(4)、β-Al_(12)(Cr,Fe)_(3)Si_(2)相。添加Cr元素能够提高合金的过冷度,对细化合金组织具有积极作用。当Cr质量分数为0.3%时,铸造合金组织细化变质效果及其力学性能最好,抗拉强度、伸长率分别为182.88 MPa、3.38%。

ZL101-xCr(x=0,0.1,0.2,0.3,0.5,0.8,wt%)aluminum alloys were prepared by vacuum electromagnetic induction melting furnace.Using OM,XRD,SEM,EDS and TEM,the microstructures of ZL101 alloys with different Cr contents were characterized,and their mechanical properties were tested.The results show that the main phases of ZL101 alloy include primaryα-Al,(α-Al+Si)eutectic,Al13Cr4Si4,β-Al_(12)(Cr,Fe)_(3)Si_(2),and Fe-rich phases(β-Al5FeSi andπ-AlSiMgFe).The microstructure of ZL101 alloys after adding trace element Cr is refined.With the increase in Cr content,theα-Al dendrites tend to be equiaxed,the eutectic structure area becomes narrow,and the Fe-rich phase and eutectic Si size become smaller.Al13Cr4Si4 andβ-Al_(12)(Cr,Fe)_(3)Si_(2)phases are formed in the alloy eutectic structure.Adding Cr element can improve the undercooling degree of the alloy,which has a positive effect on refining the alloy structure.When the Cr content is 0.3wt%,the microstructure refinement and modification effect and mechanical properties of the cast alloy are the best,and the tensile strength and elongation are 182.88 MPa and 3.38%,respectively.