摘要
为了在镁合金表面获得远离平衡态的极端快速冷却结构,对AZ31B镁合金进行了在液氮环境下极端快速冷却的CO_2激光表面重熔处理,并对该重熔层的微观结构、性能和强化机制进行了分析研究。结果表明:远离平衡态结晶凝固的镁合金表面重熔层的晶粒高度细化,且晶粒大小基本均一。重熔层主要为α-Mg,以及沿晶界析出的极少量β-Mg_(17)Al_(12)。极端快速冷却条件获得的远离平衡态的重熔层的强化机制主要为细晶强化、超固溶强化和位错强化。在此强化作用下重熔层的显微硬度HV提高到1400 MPa,磨损失量比空气冷却条件下的少50%,耐磨性显著提高。该重熔层的冲击断口特征显示出了塑性变形的痕迹,故该镁合金表面的塑性和韧性也得到了改善。
In order to obtain extremely rapid solidification structure far from equilibrium,the surface of AZ31 B magnesium alloy was melted by CO_2 laser,while the samples were extremely rapidly cooled in liquid nitrogen.The microstructure,the performance and the strengthening mechanism of the laser melted layer were investigated.The results show that grains of the melted layer are highly refined and the grain size is nearly uniform.The melted layer contains α-Mg and β-Mg_（17）Al_（12）,but β-Mg_（17）Al_（12） which distributes along the grain boundary is few.Because of strengthening mechanisms of fine grains,super solid solution and dislocation,microhardness HV of the melted layer is up to 1400 MPa.Wear loss of the melted sample cooled in liquid nitrogen is about 50%less than that of the untreated sample and the melted sample cooled in air,and wear resistance of the melted layer is improved obviously.Impacting fracture morphology indicates that there is a trace of plastic deformation,thus,improving plasticity and ductility.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2016年第8期1949-1955,共7页
Rare Metal Materials and Engineering
基金
National Natural Science Foundation of China(51075293)
Supported by Shanxi Scholarship Council of China(2013-029)
关键词
镁合金
激光重熔
非平衡
组织
性能
magnesium alloy
laser melting
nonequilibrium
microstructure
performance
