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97W表面激光合金化涂层微观组织与动态力学性能

Microstructure and dynamic mechanical properties of laser alloyed coating on 97W surface

  • 摘要: 为提高钨重合金的动态力学性能,采用激光合金化工艺在97W基体表面制备了65W10Cr5V4Co2和65W10Cr5V4Co2 + 2%C3N4复合涂层. 借助扫描电子显微镜、分离式霍普金森压杆等试验仪器,对合金化试样进行微观组织、显微硬度和动态压缩力学性能研究,采用分离变量法拟合无涂层钨合金以及带涂层钨合金的Johnson-Cook本构关系,探讨了复合涂层对97W合金动态力学性能的影响. 结果表明,含有2% C3N4的复合涂层生成了(Fe,Cr)4W2N和(Fe,Cr)3W3C等复杂的碳化物和氮化物,组织呈现规则的网状结构,元素分布更均匀,晶粒尺寸更小,熔覆层平均显微硬度达到97W基体的2.3倍;复合涂层的添加提高了整体结构材料的应变强化程度,但整体材料的应变率敏感程度有所降低,在应变率加载范围为3 500 s −1级别条件下,整体结构以W颗粒解理形式失效.

     

    Abstract: In order to improve the dynamic mechanical properties of tungsten heavy alloys, 65W10Cr5V4Co2 and 65W10Cr5V4Co2 + 2%C3N4 composite coatings were prepared on the surface of 97W matrix by laser alloying process. With the help of scanning electron microscope, separated Hopkinson press rod and other experimental instruments, the microstructure, microhardness and dynamic compression mechanical properties of the alloyed specimens were studied, and the Johnson-Cook ontological relationship of uncoated tungsten alloy and tungsten alloy with coating was fitted by using the method of separation of variables to explore the influence of composite coatings on the dynamic mechanical properties of 97W alloy. The results show that: the composite coating containing 2% C3N4 generates complex carbides and nitrides such as (Fe, Cr)4W2N and (Fe, Cr)3W3C, and the organization presents a regular reticulation structure with more uniform element distribution and smaller grain size, and the average microhardness of the fusion-coated layer reaches 2.3 times of that of the 97W matrix; the addition of the composite coating improves the degree of strain reinforcement in the overall structural material, but the The strain rate sensitivity of the overall material is reduced, and the overall structure fails in the form of W particle disintegration under the strain rate loading range of 3500 s−1 level.

     

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