Microstructure and Properties of High-Entropy AlxCoCrFe2.7MoNi Alloy Coatings Prepared by Laser Cladding

Abstract

High-entropy AlxCoCrFe2.7MoNi (x = 0, 0.5, 1.0, 1.5, 2.0) alloy coatings were prepared on pure iron by laser cladding. The effects of Al content on the microstructure, hardness, wear resistance and corrosion resistance of the coatings were studied. The results showed that the crystal phases of the AlxCoCrFe2.7MoNi coatings changed from Mo-rich BCC1 + FCC to (Al, Ni)-rich BCC2 + Mo-rich BCC1 when x increased from 0 to 0.5, and the phase changed to an (Al, Ni)-rich BCC2 + (Mo, Cr)-rich σ phase as x increased further. The hardness of the coatings increased as the Al content increased. The Al2.0CoCrFe2.7MoNi coating exhibit best wear resistance. Addition of Al increased the corrosion potential in a 3.5 wt.% NaCl solution, and the coating with x = 1.0 exhibited the highest corrosion resistance.

Microstructure Evolution and Properties of Laser Cladding CoCrFeNiTiAlx High-Entropy Alloy Coatings

“…This also confirms the results of previous studies, because laser cladding has a higher cooling rate, the higher solidification rate is beneficial to the formation of BCC phase and improves the hardness. [6,12,26,27]. The introduction of Ti element can promote the passivation behavior of the coating due to the formation of TiO 2 and Ti 2 O 3 phases.…”

“…At the same time, according to the previous calculation of the crystallite size, it can be proved that when x = 0.5, the crystallite size difference between the BCC1 and BCC2 phases is the smallest, so its corrosion resistance performance is the best. Figure 10 shows the comparison of the self-corrosion potential Ecorr and the self-corrosion current density Icorr of the six HEAs: CoCrFeNiTiAlx, CoCrFeNi, AlxCoCrFeNi, AlxCoCrFeMnNi, CoCrFeNiAiTix, and AlxCoCrFe2.7NiMo [6,12,26,27]. The introduction of Ti element can promote the passivation behavior of the coating due to the formation of TiO2 and Ti2O3 phases.…”

Complex Concentrated Alloys (CCAs)—Current Understanding and Future Opportunities

“…Eight research articles, four reviews, and one perspective have been published in this special issue of Metals. The subjects are multidisciplinary and divided into several topics including: (i) simulation and modeling for predicting structure and properties [1], (ii) unique deformation mechanisms in multi-principal alloys [2][3][4], (iii) microstructure and properties resulting from various processing routes [5][6][7][8][9][10], (iv) corrosion and surface degradation behavior [11,12], and (v) perspectives on ways to design mechanically and functionally advanced concentrated alloys [13]. Beyramali Kivy et al [1] reviewed the computational tools for studying the structure and properties of multi-principal alloys and identified the advantages as well as limitations of simulations in accelerating design and development of new alloys.…”

“…The processing-microstructure-properties relationship in complex concentrated alloys are discussed in one review article and five research papers in this special issue [5][6][7][8][9][10]. Dong et al [5] reviewed the structure, evolution in properties, and deformation behavior of HEAs after high-pressure treatment (HPT).…”

“…Zhang et al [7] evaluated the distribution in microstructure and mechanical properties of HEAs obtained after spark plasma sintering (SPS). Sha et al [8] and Zhao et al [9] researched the effect of chemical composition on the microstructure and properties of Al x CoCrFe 2.7 MoNi and Al x CoCrFeNiTi 0.5 HEAs, respectively. Increase in Al content led to an increase in hardness and wear resistance [8] and a change in erosion mode from ductile to brittle [9].…”