挤压铸造铝铜合金的组织与力学性能研究

Study on the Microstructure and Mechanical Properties of Aluminum Copper Alloy by Squeezing Casting

采用金相显微镜、扫描电镜和拉伸试验机等手段,研究了Mn/Fe比例和挤压压力对Al-Cu合金显微组织与力学性能的影响,揭示了Al-Cu合金中富铁相的存在形式和作用机理。结果表明,T6热处理态Al-Cu合金中存在针状β-Fe(Al_(7)Cu_(2)Fe)相和块状Al_(7)Cu_(2)(FeMn)相;随着Mn/Fe比例的增加,Al-Cu合金中块状Al_(7)Cu_(2)(FeMn)相的体积分数逐渐增加,而针状β-Fe相的体积分数逐渐降低,在Mn/Fe比例为为1.2和1.5时合金中都为块状富铁相;相较于挤压压力为0的Al-Cu合金,在施加75 MPa挤压压力后,相同Mn/Fe比例的Al-Cu合金中的富铁相都更为细小和分散;当挤压压力为0时,Al-Cu合金在Mn/Fe比例为1.2时达到抗拉强度、屈服强度和断后伸长率的最大值;当挤压压力为25 MPa和75 MPa时,Al-Cu合金在Mn/Fe比例为0.9时取得抗拉强度和屈服强度最大值,而断后伸长率随着Mn/Fe比例增加而略有降低。

The effect of different Mn/Fe ratio and extrusion pressure on the microstructure and mechanical properties of Al-Cu alloy was studied by means of metallographic microscope,scanning electron microscope,and tensile testing machine,and the research revealed the existing form and effect mechanism of iron rich phase in AlCu alloy.The results showed that there existed needle like beta-Fe(Al_(7)Cu_(2)Fe) phase and bulk Al_(7)Cu_(2)(FeMn)phase in T5 heat treated Al-Cu alloy.With the increase of the proportion of Mn/Fe,the volume fraction of bulk Al_(7)Cu_(2)(FeMn) phase increased gradually,while the volume fraction of acicular beta-Fe phase decreased gradually,and when the ratio of Mn/Fe was 1.2 and 1.5,only bulk Al_(7)Cu_(2)(Fe Mn) phase in the alloy.Compared to the Al-Cu alloy with extrusion pressure of 0,the iron rich phase in Al-Cu alloy with the same Mn/Fe ratio was more fine and dispersed after applying 75 MPa extrusion pressure.When the extrusion pressure was 0,Al-Cu alloy got the maximum value of the tensile strength,yield strength and elongation with the Mn/Fe ratio was 1.2.When the extrusion pressure was 25 MPa and 75 MPa,Al-Cu alloy got the maximum value of the tensile strength and yield strength with the Mn/Fe ratio was 0.9,and the elongation slightly decreased with the increasing proportion of Mn/Fe,which were mainly related to the type,size and distribution of iron rich phase in the alloy.