高性能Al-5Mg-2Si-xCe合金的制备及其力学性能研究

Preparation and mechanical properties of high performance Al-5Mg-2Si-x Ce alloy

以Al-5Mg-2Si合金为基体合金,通过掺杂稀土Ce元素对合金进行改性,制备了不同Ce掺量的Al-5Mg-2Si-xCe(x=0,0.2,0.4和0.6)合金。采用XRD、SEM、EDS和力学性能分析等方式,研究了合金的结构、微观形貌和力学性能。结果表明,Al-5Mg-2Si-xCe(x=0,0.2,0.4和0.6)合金主要由α相组合而成,掺杂Ce元素后出现了Al_(8)CeFe_(4)三元含铁相的化合物,说明Ce具有促进β-Fe相转化成α-Fe相Al_(8)CeFe_(4)的作用;不掺杂Ce元素的Al-5Mg-2Si合金的枝晶排列紊乱且尺寸较为粗大,掺入稀土Ce元素后,枝晶的排列得到了明显改善,并且随着Ce掺量的增加,晶粒逐渐细化,分布更为均匀,α-Al的尺寸也逐渐缩小;当Ce掺量为0.4%(质量分数)时,合金的抗拉强度和延伸率均达到最佳,分别为133.70 MPa和1.64%,相比Ce掺量为0时,分别增长了26.49%和115.79%;未掺杂Ce的合金主要为解离断裂,掺入Ce后,合金的断裂方式主要为延晶断裂,且断口处晶粒均较为完整未被拉裂。

Al-5Mg-2Si-x Ce(x=0,0.2,0.4 and 0.6)alloys with different Ce contents are prepared by doping rare earth Ce into Al-5Mg-2Si alloy.The microstructure,microstructure and mechanical properties of the alloy are studied by XRD,SEM,EDS and mechanical properties analysis.The results show that Al-5Mg-2Si-x Ce(x=0,0.2,0.4 and 0.6)alloys are mainly composed ofαphase.After doping Ce,the ternary compound containing iron Al_(8)CeFe_(4) appears,which indicates that Ce could promote the transformation ofβ-Fe phase intoα-Fe phase Al_(8)CeFe_(4).The dendrite arrangement of Al-5Mg-2Si alloy without Ce element is disordered and its size is relatively coarse.After Ce element is added,the dendrite arrangement is obviously improved.With the increase of Ce content,the grain is gradually refined,the distribution is more uniform,and the size ofα-Al is gradually reduced.When the content of Ce is 0.4 wt%,the tensile strength and elongation of the alloy reach the best,which are 133.70 MPa and 1.64%,respectively.Compared with 0 Ce content,the tensile strength and elongation increase by 26.49%and 115.79%respectively.The main fracture mode of the alloy without Ce doping is dissociation fracture.After Ce doping,the main fracture mode of the alloy is intergranular fracture,and the grains at the fracture are relatively complete without tensile fracture.