Al含量及均匀化处理对Mg-Al二元合金组织及阻尼性能的影响

Effect of Al content and homogenization on microstructure and damping properties of Mg-Al binary alloys

采用光学显微镜、X射线衍射仪、扫描电镜以及拉伸试验机等研究了Al含量(0.25%、0.5%、1.0%,质量分数)及均匀化处理(420℃×24 h)对铸态Mg-Al合金显微组织、力学性能和阻尼性能的影响。结果表明:Al元素的添加可以减小合金的平均晶粒尺寸,且添加量越多,平均晶粒尺寸越小,而均匀化处理后的平均晶粒尺寸明显增加。随着Al含量的增加,铸态Mg-Al合金的力学性能逐渐增加,Mg-1.0%Al合金的抗拉强度、屈服强度和伸长率均最高,分别为148.320 MPa、135.862 MPa和8.467%。均匀化处理后Mg-Al合金平均晶粒尺寸的增大导致力学性能有所下降,而Mg-0.5%Al和Mg-1.0%Al合金的伸长率较铸态有所增加。Mg-Al合金的阻尼性能与Al含量呈负相关,同时临界应变振幅随Al含量的增加而逐渐增加,铸态Mg-1.0%Al合金在应变振幅点ε_(0.1)的阻尼值Q^(-1)为0.1160,属于高阻尼镁合金范畴(Q^(-1)≥0.01),而均匀化处理后Mg-Al合金的阻尼值均较铸态有所增加。当频率一定时,Mg-Al合金的阻尼性能随着Al含量的增加而减小,当Al含量一定时,阻尼性能随着频率的增加而减小,均匀化处理对高温时阻尼性能的影响不明显。

Effects of Al content(0.25%,0.5%and 1.0%,mass fraction)and homogenization(420℃for 24 h)on microstructure,mechanical properties and damping properties of as-cast Mg-Al alloys were investigated by using optical microscope,X-ray diffractometer,scanning electron microscope and tensile testing machine.The results show that the addition of Al element reduces the average grain size of the alloy,and the more the addition,the smaller the average grain size,while the average grain size significantly increases after homogenization.The mechanical properties of as-cast Mg-Al alloy gradually increase with the increase of Al content,and the tensile strength,yield strength and elongation of the Mg-1.0%Al alloy are 148.320 MPa,135.862 MPa,and 8.467%,respectively.After the homogenization,the mechanical properties of Mg-Al alloy decrease due to the increase of average grain size,while the elongation of Mg-0.5%Al and Mg-1.0%Al alloys is increased compared to the as-cast state.The damping properties of the Mg-Al alloys decrease with the increase of Al content,and the critical strain amplitude gradually increases,the damping value Q^(-1)for the as-cast Mg-1.0%Al alloy at ε_(0.1)is 0.1160,which belongs to the category of highly damped magnesium alloys(Q^(-1)≥0.01),meanwhile,the damping values of the Mg-Al alloys after homogenization is all higher than that of as-cast state.The damping properties decreases with the increase of Al content for a specific frequency,and decreases with the increase of frequency when the Al content is constant,and the effect of homogenization on the damping properties at high temperatures is not apparent.