摘要
以AZ61镁合金为基础合金,研究了镁合金中不同稀土含量对其组织及室温力学性能的影响,并通过SEM对断口形貌的观察分析了稀土对合金断裂机制的影响。结果表明:加入1%-4%的稀土后,铸态AZ61合金组织中的母相明显变少,形成粗大针状或者棒状甚至块状AhCe或Al3Nd稀土相,造成合金成分的不均匀,使晶界脆化,同时在拉伸过程中易在粗大稀土相的尖角处形成应力集中,降低了镁合金室温力学性能;另外,由于稀土含量偏高,AZ6l合金中β-Mg177Al12相由连续网状、块状变为断续的网状或粒状,分布在合金基体中,同时沿晶界或晶内分布的粗大或团簇的Al4Ce或Al3Nd强化相,造成一定的品格畸变,阻碍位错的运动,使含稀土合金的室温力学性能有所提高,但仍低于AZ61合金的力学性能;通过SEM对断口观察发现所有试验合金的断裂方式均为解理断裂。
Influences of RE addition on the microstructures and mechanical properties, as well as the fracture mechanics of the AZ61 magnesium alloys have been investigated. The results show that after addition of ( 1%-4% ) RE, the β-Mg17Al12 phase in the as-cast alloy decreases obviously, and form coarse needle-like, clav'rform or irregularity massive Al4Ce and Al3Nd phases, which results in the un-uniformity of alloy composition and makes the grain boundary embrittlement. At the same time the stress concentration is easy to form at the sharp-angle of coarse RE phase, which reduces room temperature mechanical properties of AZ61 alloys during tensile test. In addition, for high content of RE,β-Mg17Al12 phase in AZ61 alloy changes from the continuous mesh and block into intermittent or granular shape and distributes in the matrix, in the mean while the coarse or cluster Al4Ce or/and Al3Nd strengthen phases distributing at the grain boundary result in lattice distortion and impede dislocation movement, therefore the mechanical properties of alloys with RE are improved, but still worse than that of AZ61 alloy. The fracture mechanism of AZ61+xRE alloy is cleavage.
出处
《铸造》
CAS
CSCD
北大核心
2009年第6期593-597,共5页
Foundry
关键词
AZ61+xRE镁合金
显微组织
室温力学性能
断裂机制
AZ61+xRE magnesium alloys
microstructure
room temperature mechanical properties
fracture mechanism