(1. 山東科技大學(xué) 材料科學(xué)與工程學(xué)院，青島 266950；
2. 日照鋼鐵控股集團有限公司，日照 276806)
摘 要: 利用高能等離子束對AZ91D鎂合金表面進行快速加熱重熔處理，利用X射線衍射、掃描電鏡、電子探針等對重熔層的物相、組織結(jié)構(gòu)和成分進行分析，通過摩擦和拉伸試驗研究重熔層的耐磨性和強度。結(jié)果表明：等離子束重熔層的晶粒得到高度細(xì)化，晶粒為細(xì)小的等軸晶粒，尺寸為1~2 μm；物相組成仍然為α-Mg+β-Mg17Al12，但α-Mg相減少，β-Mg17Al12增加，且β-Mg17Al12相的分布更加均勻彌散；重熔層深度與等離子束的電流大小有關(guān)，電流越大，熔凝層越深；重熔層的顯微硬度(105~125 HV0.1)明顯高于基體的顯微硬度(60~70 HV0.1)，拉伸斷口細(xì)致，有塑性變形痕跡以及由細(xì)小均勻韌窩組成的纖維狀的撕裂痕，也有明顯的晶粒拔出痕跡，等離子重熔處理有利于提高AZ91D鎂合金的表面耐磨性和強度。
關(guān)鍵字: 鎂合金；等離子束重熔；細(xì)晶強化；固溶強化
AZ91D magnesium alloy remelted by plasma beam
（1. School of Materials Science and Engineering, Shandong University of Science and Technology,
Qingdao 266950, China;
2. Rizhao Steel Holding Group Co., Ltd., Rizhao 276806, China）
Abstract:The plasma-remelting layer on the surface of AZ91D magnesium alloy was obtained by high energy density plasma beam treatment. The microstructure, composition, wear resistance and intensity of the plasma-remelting zone were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), electron probe X-ray microanalyser (EPMA), friction tester and tension tester, respectively. The results show that the plasma-remelting layer is still composed of α-Mg and β-Mg17Al12 with fine texture. The crystalline grains are equiaxial with size of 1−2 μm. However, the content of α-Mg decreases while β-Mg17Al12 increases, whose distribution becomes more uniform. The depth of the plasma-remelting zone depends on the current intensity of the beam. The larger the current is, the deeper the depth is. Compared with 60−70 HV0.1 of the substrate, the microhardness of the remelting layer reaches up to 105−125 HV0.1. The tensile fracture is fine with plastic deformation trace. The tiny evenly fibroid tearing trace forms dimple and there are obvious grain uproot trace. The plasma remelting treatment is helpful to improve the wear resistance and intensity of the surface of AZ91D magnesium alloy.
Key words: magnesium alloy; plasma beam remelting; solid solution strengthening; dispersion strengthening
