摘要
以纯度为99.7%的工业纯铝、99.9%的工业纯镁和Al-10%Er的中间合金为原料,采用铸锭冶金法制备3种不同名义成分的目标合金,研究稀土元素Er对Al-Mg合金显微组织及力学性能的影响。结果表明:Er明显地降低了合金的屈服强度、抗拉强度和伸长率。当Er的添加量(质量分数)为0.4%和1%时挤压态Al-Mg合金的抗拉强度(σb)分别下降82 MPa和40 MPa,屈服强度(σ0.2)分别下降13 MPa和11 MPa,伸长率(δ)分别下降11.3%和4.5%。显微组织分析表明,添加Er在基体中形成粗大的含Er和Mg的结晶相导致Mg在铝基体中的固溶度下降,从而减少了溶质原子与位错的交互作用,导致合金的屈服强度降低。在变形过程中,粗大的含Er和Mg的结晶相由于应力集中在较低的应力下发生断裂而形成微裂纹,微裂纹以较快的速率扩展至基体晶界,形成一种典型的韧脆混合断裂,使合金的抗拉强度和伸长率减小。
The effects of rare-earth element Er on microstructures and mechanical properties of Al-Mg alloy were studied using Instron 8082 testing machine, SEM and TEM. It has been shown that the addition of Er obviously decreases the yield strength, tensile strength and elongation of the Al-Mg alloy. When the content of Er reaches 0.4% and 1%, the tensile strength of Al-Mg alloy has been decreased by 82 MPa and 40 MPa, respectively; the yield strength has been decreased by 13 MPa and 11 MPa, respectively; and the elongation has been decreased by 11.3% and 4.5%, respectively. Microstructural analysis indicates that coarse constituents with Er and Mg have been formed in the alloys with the addition of Er, and thereby reduce the solubility of Mg in the matrix. The reduction of solubility of Mg decreases the interaction between solute atoms and dislocations, and thus decreases the yield strength of the alloys. During deformation, the constituents with Er and Mg will fracture first and act as microcrack sources due to the stress concentration. The microcracks spread rather quickly to grain boundary of the matrix, leading to the decreases in tensile strength and elongation.
出处
《粉末冶金材料科学与工程》
EI
2008年第4期229-234,共6页
Materials Science and Engineering of Powder Metallurgy
基金
湖南省自然科学基金资助项目(07JJ3117)
