Mn、Yb含量对非热处理铝镁合金组织和性能的影响

Effect of Mn and Yb Contents on Microstructure and Properties of Non-heat Treated Al-Mg Alloy

为了提升非热处理铝镁合金力学性能,设计了不同Mn、Yb含量的铝镁合金,采用室温拉伸、硬度测试、摩擦磨损测试和OM、SEM显微观察等实验,研究了不同Mn、Yb含量对铝镁合金微观组织、力学性能和耐磨性能的影响,得到最优Mn、Yb含量的铝镁合金。结果表明,Mn元素的加入减弱了镁元素引起的枝晶偏析,在铝基体中形成弥散分布的细小化合物Al6Mn,该化合物促进了晶粒的形核,从而抑制晶粒长大,使晶粒得到细化,改善合金组织;稀土元素Yb改善了第二相的分布且形成细小的Al3Yb作为异质形核核心,提高形核率,使得铸件组织中的晶粒数增加,晶粒变小,从而改善铝镁合金组织。当Mn、Yb含量均为0.6%时,合金的力学性能和耐磨性能最佳。合金的硬度为73.75 HBS,抗拉强度为278 MPa,屈服强度为214 MPa,伸长率为10.53%,磨损率为5.88%,与不含Yb元素的合金相比,布氏硬度、抗拉强度和屈服强度分别提高了20.31%、10.31%和19.55%,磨损率降低了2.08%。

In order to improve the mechanical properties of non-heat treated aluminum-magnesium alloys,aluminum-magnesium alloys with different Mn and Yb contents are designed.The effects of different Mn and Yb contents on the microstructure,mechanical properties and wear resistance of aluminum-magnesium alloys are studied through room temperature stretching,hardness testing,friction and wear testing,OM and SEM microscopic observation experiments,etc.,and the optimal Mn and Yb contents are obtained.The results show that the addition of Mn weakens the dendrite segregation caused by magnesium,forming a dispersed fine compound Al6Mn in the aluminum matrix,which promotes the nucleation of the grains,thus inhibiting the grain growth,refining the grains and improving the microstructure of the alloy.The rare earth element Yb improves the distribution of the second phase and forms fine Al3Yb as the heterogeneous nucleation core,which increases the nucleation rate,increases the number of grains in the casting structure and decreases the grains,thus improving the microstructure of Al-Mg alloy.When the content of Mn and Yb is 0.6%,the mechanical properties and wear resistance of the alloy are the best.The hardness of the alloy is 73.75 HBS,the tensile strength is 278 MPa,the yield strength is 214 MPa,the elongation is 10.53%,and the wear rate is 5.88%.Compared with the alloy without Yb element,the Brinell hardness,tensile strength and yield strength are increased by 20.31%,10.31%and 19.55%,respectively,and the wear rate is reduced by 2.08%.