Al-Cu-Mn-Fe-Ag-Zr合金的微观组织与室温和高温性能研究

Study of the Microstructure and Room-and High-Temperature Properties of an Al-Cu-Mn-Fe-Ag-Zr Alloy

Al-Cu合金具有低密度、耐热性好和潜在的高温稳定性等优点,广泛应用于汽车和航空航天等领域。为提高Al-Cu基铸造合金的耐热性能,本文制备了质量分数为Al-4%Cu-0.5%Mn-0.1%Fe-0.4%Ag-0.3%Zr(简称AC)的合金。采用OM和SEM分析了合金的微观形貌及化学成分,采用XRD分析了合金的物相结构,采用EBSD研究了晶粒形态与尺寸分布,采用TEM分析了合金在时效处理后的微观组织和析出相形态,采用高低温拉伸试验机进行了室温和高温力学性能测试。结果表明,AC合金在铸造过程中形成的金属间化合物主要包括Al_2Cu和Al_7Cu_2Fe,其中,Al_2Cu相在固溶处理后溶入基体中,并在时效处理后重新沉淀为θ′相,成为主要的强化相。此外,经T6热处理后,合金中还包含着T_(Mn)(Al_(20)Cu_2Mn_3)相,Ag元素固溶于铝基体中,而Zr元素则使得合金析出L1_2-Al_3Zr纳米相,其与θ′相存在位向关系。测试了合金在室温和高温(200、300和400℃)下的拉伸性能,对应屈服强度可分别达236、155、129和61 MPa。

Al-Cu alloys are widely used in automotive and aerospace applications due to their low density,good heat resistance and potential high-temperature stability.To improve the heat resistance of Al-Cu casting alloys,an alloy with a mass fraction of Al-4%Cu-0.5%Mn-0.1%Fe-0.4%Ag-0.3%Zr(AC)was prepared.The microscopic morphology and chemical composition of the alloy were analysed by OM and SEM,the phase structure was analysed by XRD,the grain morphology and size distribution were investigated by EBSD,the microstructural details and precipitated phases after aging treatment were analysed by TEM,and the mechanical properties at room temperature and high temperature were tested by a tensile testing machine.The results show that the intermetallic compounds that formed during the casting process of the AC alloy include Al2Cu and Al7Cu2Fe.The Al2Cu phase dissolves into the matrix after solid solution treatment and reprecipitates as theθ′phase after aging treatment,acting as the main strengthening phase.After T6 heat treatment,the alloy also contains the TMn(Al20Cu2Mn3)phase.Moreover,Ag dissolves in the Al matrix,and the addition of Zr leads to the precipitation of the L12-Al3Zr nanophase,which coincides with the location of theθ′precipitated phase.The tensile properties of the alloys were tested at room and high temperatures(200,300 and 400℃),and the yield strengths are 236,155,129 and 61 MPa,respectively.