Abstract
The corrosion behaviors of equiatomic CoCrFeMnNi high-entropy alloys (HEAs) were comparatively investigated between selective laser melting (SLM) and casting. The casted sample shows better corrosion resistance in 3.5 wt. % NaCl solution than the SLM printed samples 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 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.
Highlights
High entropy alloys (HEAs) consist of five or more metallic elements with equimolar or nearequimolar ratios, which feature satisfying properties, such as excellent mechanical properties, predominant corrosion resistance, magnetism and high resistivity (Ye et al, 2016)
This paper systematically studied the corrosion behavior of CoCrFeMnNi HEA alloys between traditional casting and Selective laser melting (SLM)
All of the curves feature flat fluctuation after 6 days of immersion. It indicates that the corrosion products and dense oxide layers are formed after the surface corrosion (Gu et al, 2012), which reduces the weight loss rate
Summary
High entropy alloys (HEAs) consist of five or more metallic elements with equimolar or nearequimolar ratios, which feature satisfying properties, such as excellent mechanical properties, predominant corrosion resistance, magnetism and high resistivity (Ye et al, 2016). Selective laser melting (SLM), as one of the additive manufacturing (AM) method, can produce a three-dimensional model with highly complex geometric features and ultrafine microstructure (Joseph et al, 2017; Li L. et al, 2020; Li R. et al, 2020; Niu et al, 2020). Compared to the traditional casting and forging process, SLM has many advantages such as the simplified manufacturing procedures and the capacity of fabricating parts with high geometry complexity (Chen et al, 2017). The SLM-produced metallic parts have a more homogenized microstructure and better properties because of its high solidification rate (105 Ks−1) (Niu et al, 2019). Zhang et al (2018) studied the thermal-mechanical behavior of a SLM produced WTaMoNb refractory HEA, which exhibits better properties than its casted counterparts.
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