论文部分内容阅读
采用OM,SEM,TEM,XRD等手段,研究了不同状态的GWN751K镁合金的组织和性能。结果表明:铸态合金主要由基体和网状共晶组织构成,σb=215MPa,σ0.2=187MPa,δ=3.5%,DSC曲线存在明显的低熔点吸热峰;经过535℃,16h热处理,共晶组织分解,晶界残留富Mg-Y相,晶粒尺寸明显长大,合金的力学性能有所改善,σb=240MPa,σ0.2=189MPa,δ=10%,DSC曲线低熔点吸热峰消失;合金经过挤压后,发生动态再结晶,力学性能显著提高,σb=320MPa,σ0.2=260MPa,δ=18%,最主要的原因是挤压后合金中存在高密度位错以及细小的晶粒,可显著提高合金的强度和塑性;经过时效后,合金的平均断裂强度达到400MPa以上,但塑性明显降低。铸态合金二次裂纹主要存在于晶界的共晶组织中,535℃,16h热处理以及挤压后的合金二次裂纹主要是在晶粒内部。
The microstructure and properties of GWN751K magnesium alloy with different states were investigated by means of OM, SEM, TEM and XRD. The results show that the as-cast alloy is mainly composed of matrix and reticular eutectic structure with σb = 215MPa, σ0.2 = 187MPa and δ = 3.5%. The DSC curve shows a distinct low melting endothermic peak. After 535 ℃ and 16h heat treatment, The eutectic structure is decomposed, the Mg-Y phase remains in the grain boundary, and the grain size obviously grows. The mechanical properties of the alloy are improved. Σb = 240MPa, σ0.2 = 189MPa, δ = 10% The peak disappears. The dynamic recrystallization of the alloy occurs after extrusion. The mechanical properties of the alloy are obviously improved. The main reason is the high density dislocation in the alloy after extrusion and The fine grains can significantly improve the strength and ductility of the alloy. After aging, the average breaking strength of the alloy reaches more than 400MPa, but the ductility obviously decreases. The as-cast alloy secondary cracks mainly exist in the grain boundary eutectic structure, and the secondary cracks after heat treatment and extrusion at 535 ℃ and 16h are mainly in the grain interior.