A new method of preparing high-performance high-entropy alloys through high-gravity combustion synthesis
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A new method of preparing high-performance high-entropy alloys through high-gravity combustion synthesis Fu-kai Zheng 1,2), Guan-nan Zhang 3), Xiu-juan Chen 1,2), Xiao Yang 3), Zeng-chao Yang 3), Yong Li 3), and Jiang-tao Li 3) 1) College of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China 2) College of Mechano-Electronic Engineering, Lanzhou University of Technology, Lanzhou 730050, China 3) Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China (Received: 24 December 2019; revised: 23 February 2020; accepted: 24 February 2020)
Abstract: A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr0.9FeNi2.5V0.2Al0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients. Keywords: high-entropy alloys; high gravity; combustion synthesis; post-treatment; low-cost; high performance
1. Introduction High-entropy alloys (HEAs) have received extensive attention due to their special composition and microstructure [1–7]. For a long time, most studies have focused on realizing excellent mechanical properties. In particular, Cr0.9FeNi2.5V0.2Al0.5 alloy with good plasticity and ultrahigh yield strength up to 1700–1900 MPa has been explored based on precipitation strengthening mechanism [8]. In general, arc melting, induction melting, mechanical alloying, electrochemical deposition, laser cladding, and many other conventional preparation methods have been adopted to fabricate HEAs. However, to obtain the excellent properties of the material, the expensive high-purity metals such as Cr, Ni, and V must be used as raw materials, which results in high manufacturing cost and serious restrictions in engineering applications. Therefore, to promote the practical use of HEAs, reducing the production cost is necessary, and this requires the development of a new material preparation technology that is not dependent to expensive metal materials.
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