摘要:
将真空常压烧结方法制得的Cr3C2-Ni2Al 复合焊丝堆焊于碳钢表面。分析表明, 在堆焊过程中, 利用氩弧物理热和Ni-Al 反应热, Ni 与Al 化合反应生成Ni3Al 金属间化合物, Cr3C2 则发生分解, 除少部分[ C]与[Cr ]固溶于Ni3Al 基体中外, 大部分反应析出更稳定的Cr7C3 相, 其尺寸取决于堆焊层中不同区域的冷却环境,较为均匀地分布于Ni3Al 基体中。由于Cr 在Ni3Al 中的固溶度远大于C , 加之Cr3C2 转化为Cr7C3 也造成部分富余的C , 结果造成在该Ni3Al 表面强化材料焊层中形成石墨相, 其密度轻、熔点高, 主要偏聚于焊层表层。Cr7C3 / Ni3Al 复合材料的室温、高温硬度远高于传统高温耐磨材料Stellite 合金, 该材料有望成为一种新型的高温耐磨表面强化材料。
关键词:
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Ni3Al
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碳化铬
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高温耐磨
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溶解
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析出
Abstract:
A Cr3C2-Ni2Al welding wire was produced by pressureless sintering process in vacuum. When thewelding wires were welded on the surface of carbon steel , carbide particles reinforced Ni3Al base composite wasformed due to the physical heat of arc and Ni-Al exothermic reaction. XRD shows that Ni react s with Al to formNi3Al and Cr3C2 is dissolved during welding. Most of [Cr ] and [C] react to form Cr7C3 phase except that a few dissolve into Ni3Al mat rix. The size of Cr7C3 particles mainly depends on the cooling rate of different welding regions.In addition , as the solid solubility of Cr in Ni3Al is much larger than that of C and Cr3C2 changes to Cr7C3 duringwelding , some graphites are formed in welding layers. The graphites mainly segregate on welding outer layers dueto it s low density and high melting point . The room and high temperature hardness of Cr7C3 / Ni3Al composite ismuch higher than that of stellite alloys. It is predicted that Cr7C3 / Ni3Al composite may become an att ractive potential candidate for high2temperature surface wear-resistant material.
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