WxNbMoTa Refractory High-Entropy Alloys Fabricated by Laser Cladding Deposition.

Qingyu Li,Sheng Huang,Zihao Chen,Haoqi Yan,Hang Zhang,Zhongliang Lu,Dichen Li

doi:10.3390/ma12030533

Abstract

WxNbMoTa refractory high-entropy alloys with four different tungsten concentrations (x = 0, 0.16, 0.33, 0.53) were fabricated by laser cladding deposition. The crystal structures of WxNbMoTa alloys are all a single-phase solid solution of the body-centered cubic (BCC) structure. The size of the grains and dendrites are 20 μm and 4 μm on average, due to the rapid solidification characteristics of the laser cladding deposition. These are much smaller sizes than refractory high-entropy alloys fabricated by vacuum arc melting. In terms of integrated mechanical properties, the increase of the tungsten concentration of WxNbMoTa has led to four results of the Vickers microhardness, i.e., Hv = 459.2 ± 9.7, 476.0 ± 12.9, 485.3 ± 8.7, and 497.6 ± 5.6. As a result, NbMoTa alloy shows a yield strength (σb) and compressive strain (εp) of 530 Mpa and 8.5% at 1000 °C, leading to better results than traditional refractory alloys such as T-111, C103, and Nb-1Zr, which are commonly used in the aerospace industry.

Highlights

IntroductionTraditional alloy design is based on a metallic element with a mass fraction of more than 50% and the comprehensive properties of the alloys are improved by adding trace elements
With the rapid development of materials and manufacturing technologies in the aerospace industry, the established macroscopic thermal protection theory and the existing traditional types of the refractory alloy are difficult to meet the harsh requirements of the advanced aerospace industry.Traditional alloy design is based on a metallic element with a mass fraction of more than 50% and the comprehensive properties of the alloys are improved by adding trace elements
The purpose of the work is to study the dependence of the yield strength of the refractory high-entropy alloys (HEAs) on their composition fabricated by laser cladding deposition (LCD) for the potential applications in aerospace industry

Summary

Introduction

Traditional alloy design is based on a metallic element with a mass fraction of more than 50% and the comprehensive properties of the alloys are improved by adding trace elements. This system of alloy design has reached the bottleneck after thousands of years of development. HEAs can be defined as a simple and disordered structure of solid solution mixed by multi-elements of 5%–35% atom ratio, showing specific characteristics, such as the high-entropy effect in thermodynamics and hysteresis diffusion effect in dynamics [2,3]. These characteristics contribute to the advantages of HEAs in such aspects as high-temperature resistance [4], high strength and ductility [5,6], corrosion and radiation resistance [7,8], providing more possible applications in the aerospace industry

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