激光熔覆镍基合金与铝反应合成Ni-Al金属间化合物覆层的研究

以镍基合金和铝为原料,利用激光熔覆技术在低碳钢表面反应合成Ni-Al金属间化合物覆层。采用SEM,EDX,TEM和XRD等表征手段对试样的组织和相结构进行分析。结果表明:激光熔覆镍基合金与铝反应合金覆层由β-Ni Al和γ′-Ni3Al两相构成,两相中均固溶有一定量Fe,Si元素。β-Ni Al相含量较多,为细小、均匀、交错分布的树枝晶,Ni,Al间的反应放热使树枝晶呈现等轴化趋势;γ′-Ni3Al相含量较少,呈连续网状分布于β-Ni Al树枝晶周围,这种结构有利于降低覆层脆性。在1.5kW功率下,激光熔覆镍基合金及铝反应合成的β-Ni Al和γ′-Ni3Al两相合金覆层致密,有少量气孔但无裂纹现象,覆层与基体实现完全冶金结合。

Ni-Al Intermetallic Coatings Prepared by Laser-cladding Synthesize with Ni-based Alloy and Al

Ni-Al intermetallic compound coatings were prepared on mild steel substrate by laser-cladding synthesize with mixed powders of Ni-based alloy and Al. The coatings microstructure and phase constitution were studied with SEM, EDX, TEM and XRD. The results show that the two-phase microstructure of the coating consists mainly of β-NiAl and γ′-Ni_3Al, with a certain amount of Fe and Si are retained in both solution. β-NiAl are uniformity and staggered fine dendrites surrounded continuously by γ′-Ni_3Al, which is beneficial to reduce the coating brittleness.Compact coats jointed metallurgically with the steel are obtained on 1.5kW powers, a few pores but no cracks are also found in the claddings.