元素W对Ni6Cr4WxFe9Ti高熵合金激光熔覆涂层组织与性能的影响

Effect of Element W on Microstructure and Properties of High-entropy Alloy Ni6Cr4WxFe9Ti Laser Cladding Coatings

  • 摘要: 在多主元合金基体中引入难熔金属元素W,是实现其组织细化、提高力学性能和耐蚀性等的有效途径之一。本研究采用机械合金化与激光熔化沉积相结合的方法制备了高熵合金Ni6Cr4WxFe9Ti(x=0、0.5、1.0和1.5),在明确其形成规律的基础上,进一步分析并研究了W原子比对其组织、力学性能和耐蚀性的影响。结果表明:机械合金化4 h的Ni6Cr4WxFe9Ti合金粉末主要由FCC+BCC双相组成;经激光熔化沉积后,FCC+BCC双相组织转变为单相FCC组织。随着W元素原子比的增加,熔覆涂层的晶粒尺寸逐渐减小,Ni6Cr4W1.5Fe9Ti的晶粒尺寸最小,约为3~5 μm,且该熔覆涂层的硬度、抗压强度分别达到456HV、1 376 MPa。相较于Ni6Cr4Fe9Ti试样,Ni6Cr4W1.5Fe9Ti试样的自腐蚀电流密度降低3个数量级。本研究为复杂成分合金的制备及耐蚀性能提高提供了参考。

     

    Abstract: The introduction of refractory metal W into multi-principal alloy matrices is an effective way to refine microstructure and enhance mechanical and corrosion-resistant properties. In this work, Ni6Cr4WxFe9Ti (x= 0, 0.5, 1.0, 1.5) high-entropy alloy (HEA) cladding coating is prepared by mechanical alloying and laser melting deposition. Based on clarifying the formation mechanism of the HEAs, the influences of W atomic ratio on the cladding microstructure, and mechanical and corrosion resistance properties are investigated. The results indicate that the Ni6Cr4WxFe9Ti powders mechanically alloyed for 4 h are primarily composed of dual-phase structure of FCC and BCC. After laser melting deposition, the dual-phase structure is transformed into a single-phase FCC structure. With the increasing of W atomic ratio, the grain size of the cladding coating gradually decreases. The grain size of Ni6Cr4W1.5Fe9Ti cladding layer is the smallest, about 3-5 μm and its hardness and compressive strength reach 456 HV and 1 376 MPa, respectively. The self-corrosion current density of Ni6Cr4W1.5Fe9Ti alloy decreases by three orders of magnitude compared compared to the W-free Ni6Cr4Fe9Ti alloy. This research provides reference for the preparation of alloys with complicate compositions and the corrosion resistamce is improved.

     

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