时效对AEZ611镁合金组织及力学性能的影响

通过对挤压坯预成形AEZ611镁合金进行锻压成形及时效热处理,研究了塑性形变及时效过程中显微组织及力学性能的变化规律。结果表明,在箱式电阻炉中时效处理,晶界较粗且晶粒大小不均,油浴中时效晶界变细,有利于合金力学性能的改善。同时AEZ611镁合金力学性能及显微组织对温度较为敏感。时效温度升高至200℃时,第二相的析出速度加快,且析出相分布变得均匀,细小的黑色点状相弥散分布于晶界上;随着时效保温时间的延长,稀土相Al4Ce相在镁合金的弥散数量增加,且晶粒大小均匀,使合金的力学性能得以进一步改善,稀土的弥散数量、大小及形貌对AEZ611镁合金的力学性能有着重要的影响。最佳时效工艺为油浴中时效390℃×1h+200℃×20h,其抗拉强度可达311MPa,屈服强度达到232MPa,伸长率为11%。

Influence of Aging Treatment on Microstructure and Mechanical Properties of AEZ611 Magnesium alloy

Microstructures and mechanical properties of AEZ611 magnesium alloy extruded during of aging is investigated.The results show that grain size becomes coarse with uneven distribution in the alloy after aged in box-type resistance furnace,while it is refined in oil bathing,which is beneficial for improving the mechanical properties.In addition,mechanical properties and microstructure of the alloy are closely related with temperature.With aging temperature increased to 200 ℃,precipitation velocity of secondary phase is aclelarated with more homogeneous distribution,and fine black pit-shape phase is dispersedly distributed into grain bonundary.With increasing in holding time,precipitates of Al4Ce is increased with unform distribution,which further improves the mechanical properties of the alloy.Mechnical properties of the alloy are related with precipitates,size and morphology of RE phase.With aging at 390 ℃ for 1 h in oil bathing and at 200 ℃ for 20 h,tensile strength,yield strength and elongation of the alloy reach 311 MPa,232 MPa and 11%,respectively.