等离子堆焊镍基合金粉末的组织与性能

为了提高核电成套设备的阀体性能,利用光学显微镜、扫描电子显微镜、X射线衍射仪、电子探针显微分析仪和能谱仪分析了堆焊层的组织形态和成分分布,利用显微硬度计测量了堆焊层的硬度,利用磨损试验机分析了堆焊层的耐磨性.结果表明,堆焊层主要由过共晶组织组成,从熔合线到堆焊表面堆焊层组织依次为平面晶生长区、亚共晶组织区、共晶组织区和过共晶组织区.堆焊层金属相由γ-Ni、CrB、Cr_2B、Cr_7C_3和Cr_(23)C_6组成,初晶相由硼化物(CrB或Cr_2B)和碳化物(Cr_7C_3或Cr_(23)C_6)组成,而共晶组织主要由富(Ni,Fe)奥氏体固溶体或富Ni奥氏体固溶体组成.堆焊层表面平均硬度达到50 HV以上,约为基体硬度的3~5倍,与母材相比堆焊层的耐磨性约提高了9倍.

Microstructure and properties of Ni-based alloy powder prepared with plasma cladding

In order to improve the performance of valve body in complete nuclear power equipment, the microstructure morphology and composition distribution of cladding layer were analyzed with the optical microscope(OM), scanning electronic microscope(SEM), X ray diffractometer(XRD), electronic probe microanalysis(EPMA)and energy dispersive spectrometer(EDS), the hardness of cladding layer was measured with the microhardness tester, and the wear resistance of cladding layer was analyzed with the wear tester. The results show that the cladding layer is mainly composed of hypereutectic microstructure, and the microstructure of cladding layer includes the plane crystal growth area, hypoeutectic microstructure area, eutectic microstructure area and hypereutectic microstructure area from the fusion line to the cladding surface. The metallic phases in the cladding layer are the γ-Ni, CrB, Cr₂B, Cr₇C₃and Cr₂₃C₆ phases, the primary phase consists of boride(CrB or Cr₂B)and carbide(Cr₇C₃ or Cr₂₃C₆), and the eutectic microstructure consists of Ni and Fe-rich austenitic solid solution or Ni-rich austenite solid solution. The average hardness of cladding layer surface is above 50 HV, which is about as 3 to 5 times as that of substrate. Compared with the base metal, the wear resistance of cladding layer increases by about 9 times.