Corrosion Behavior of an Equiatomic CoCrFeMnNi High-Entropy Alloy- a Comparison Between Selective Laser Melting and Cast

Abstract

The corrosion behaviors of equiatomic CoCrFeMnNi high-entropy alloys (HEAs) were comparatively investigated between selective laser melting (SLM) and casting. The cast sample shows better corrosion resistance in 3.5 wt.% NaCl solution than the SLM printed sample due to the higher density of dislocations, pores, and cracks in SLM samples, which significantly reduces their corrosion resistance. Furthermore, it is found that the corrosion resistance is different between the planes parallel and perpendicular to the building direction of SLM sample because of the differences in grain orientation, grain size, and surface morphology. Electrochemical anode dissolution rates of the SLM printed CoCrFeMnNi HEAs on their planes parallel and perpendicular to the building direction are calculated and the results show that the pores and cracks dominate the corrosion resistance rather than the grain boundary and the grain orientation.

Microstructural Transformation and Corrosion Property Improvement of CoCrFeNiTi‐Based Multi‐Principal Element Alloys Fabricated via Laser Powder Bed Fusion

“…The equilibrium phases of Ni 3 Ti and Co 3 Ti were reported as η (D0 24 ) phase and γ 0 (L1 2 ) phase, respectively. [48][49][50] The equilibrium phase ratios in MPEA1 and MPEA2 were calculated using ThermoCalc software (TCNI6 database) (Figure 12). The calculated phase ratio of η-phase was lower in MPEA2 than in MPEA1 in all temperature ranges.…”

“…[ 46,47 ] The dense dislocation network was also suggested as a cause of lower corrosion resistance in the CoCrFeMnNi HEAs. [ 48 ] In as‐built specimens, such inhomogeneous distributions of elements and dislocations may have accelerated corrosion. Weight loss during H 2 SO 4 immersion was significantly reduced after the ST process for all specimens, possibly due to the homogenization of the microcellular structures.…”

Recent Advances in Additive Manufacturing of High Entropy Alloys and Their Nuclear and Wear-Resistant Applications

“…Apart from SPS, SLM is the most widely studied AM technique for HEAs . HEAs that were successfully fabricated by SLM include CoCrFeNiMn [153,154,169,[176][177][178][179][180][181][182][183][184][185]188,[202][203][204][205][206]209,212,214,215,217,220,221], AlCrFeNiV [193], AlCoCrFeNi [170,190], Al-CoCrCuFeNi [194], CoCrFeNi [98,155,186,187,189,208,213,222], CoCr 2.5 FeNi 2 TiW 0.5 [223],…”

“…They have also shown that the properties of HEAs could be altered by changing the input parameters for AM process. For example, CoCrFeNiMn was manufactured with SLM by multiple researchers [153,154,169,[176][177][178][179][180][181][182][183][184][185]188,[202][203][204][205][206]209,212,214,215,217,220,221] and many of them acquired different mechanical properties for CoCrFeNiMn by changing input parameters in AM processes (refer Tables 1-3).…”

Laser additive manufacturing of magnesium alloys and its biomedical applications

“…How a given HEA reacts in a corrosion environment depends on its microstructure, alloying elements, and processing methods. In recent years, corrosion resistance of CoCrFeMnNi HEA was investigated for samples produced by conventional methods [30][31][32][33] , DED [34] and SLM [35][36][37][38] . Xu et al [38] compared the corrosion properties of SLMed and as-cast CoCrFeMnNi and found that the former exhibit better corrosion resistance due to homogeneity of components and grain refinements.…”