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研究Nd对Mg-6Al铸态合金拉伸性能的影响。结果表明:室温和175℃下,Mg-6Al-xNd(x=0,2,4,6,质量分数,下同)合金的屈服强度随Nd含量增加而增加,在6.0%Nd时达到最大;抗拉强度和延伸率在4.0%Nd时达到最大,当Nd含量上升至6.0%时,两者均有少量下降。组织分析表明,Nd在Mg-6Al中以针状Al11Nd3和多边形状Al2Nd相存在,其中前者含量明显高于后者,为主要析出相。Al11Nd3相析出于枝晶界和晶界,有效细化了枝晶间距和晶粒度。通过建立软硬体复合模型对合金拉伸过程进行力学分析,并结合拉伸断口观察,综合认为Mg-6Al-xNd合金拉伸性能的提高主要归结于Al11Nd3相引起的细晶强化和第二相强化作用。Nd含量达到6.0%时合金抗拉强度和延伸率出现少量下降,主要归结于大块脆性相Al2Nd含量的增加。
The effect of Nd on the tensile properties of Mg-6Al as-cast alloy was investigated. The results show that the yield strength of Mg-6Al-xNd alloy (x = 0, 2, 4, 6, mass fraction) is increased with the increase of Nd content at room temperature and 175 ℃, Tensile strength and elongation reach the maximum at 4.0% Nd, with a slight decrease for both when the Nd content increases to 6.0%. Tissue analysis shows that Nd is present in the Al-doped Al11Nd3 and Al2Nd phases in Mg-6Al, and the former is obviously higher than the latter, which is the main precipitated phase. Al11Nd3 phase precipitated in the dendritic and grain boundaries, effectively refined the dendritic spacing and grain size. The mechanical analysis of the tensile process and the observation of tensile fracture show that the improvement of tensile properties of Mg-6Al-xNd alloy is mainly attributed to the fine grain strengthening caused by Al11Nd3 phase and the second phase Strengthen the role. When the Nd content reaches 6.0%, the tensile strength and elongation of the alloy decrease slightly, which is mainly attributed to the increase of Al2Nd content in the bulk brittle phase.