(1. 山东科技大学 材料科学与工程学院，青岛 266950；
2. 日照钢铁控股集团有限公司，日照 276806)
摘 要: 利用高能等离子束对AZ91D镁合金表面进行快速加热重熔处理，利用X射线衍射、扫描电镜、电子探针等对重熔层的物相、组织结构和成分进行分析，通过摩擦和拉伸试验研究重熔层的耐磨性和强度。结果表明：等离子束重熔层的晶粒得到高度细化，晶粒为细小的等轴晶粒，尺寸为1~2 μm；物相组成仍然为α-Mg+β-Mg17Al12，但α-Mg相减少，β-Mg17Al12增加，且β-Mg17Al12相的分布更加均匀弥散；重熔层深度与等离子束的电流大小有关，电流越大，熔凝层越深；重熔层的显微硬度(105~125 HV0.1)明显高于基体的显微硬度(60~70 HV0.1)，拉伸断口细致，有塑性变形痕迹以及由细小均匀韧窝组成的纤维状的撕裂痕，也有明显的晶粒拔出痕迹，等离子重熔处理有利于提高AZ91D镁合金的表面耐磨性和强度。
关键字: 镁合金；等离子束重熔；细晶强化；固溶强化
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
