本文研究激光快速熔凝对一种新型Ni基铸造超合金显微组织和磨蚀磨损性能的影响。 高Mo,W含量Ni基铸造合金是一种具有低膨胀系数和耐磨耐蚀等特种工程性能的新型材料。因合金中难熔重元素含量较高(33wt-％Mo,17wt-％W),其铸造组织粗大,含有大量高熔点相,并存在严重偏析。 用高能量密度激光快速熔凝表面处理之后,合金组织发生显著改变。全部高熔点相熔化,明显提高固溶度;结晶组织细化,分别为精细枝晶、胞状枝晶、胞状晶和平面凝固组织;熔区内合金元素均匀分布,基本消除偏析。 合金组织变化使其性能进一步改善,熔区硬度明显增加,提高了抗磨擦磨损和在酸性介质中的耐磨蚀性能。
Study was made of the influence of the laserglaze on the micro-structure and the wear resistance of a cast Ni-base superalloy containing abundance of refractory metals, i. e. Mo 33 wt-％ and W 17 wt-％. Owing to the high contents of Mo and W, this new alloy makes its cast structure coarse and. seriously segregated and forms a large amount of phases of higher melting point. Experimental results show that the microstructure of such superalloy may be extraordinarily improved after surface treatment by laserglaze of very high energy density. All high melting point phases vanish. The solid solubility increases greatly. The crystalline structure becomes finer. The fine dendritic, cellular dendritic, cellular and plane front solidification structures are found in various parts of melted region. In the laser melted zone, the alloying elements distribute uniformly. Thus, the segregation in the alloy may be substantially eliminated by the treatment of this new technique. The change of its microstructure favours the further improvement of the properties, e. g. , the hardness of the laser melted zone is evidently increased and the wear resistance both in dry environment and in acid medium is also enhanced.
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