Influences of Process Parameters on the Microstructure and Mechanical Properties of CoCrFeNiTi Based High-Entropy Alloy in a Laser Powder Bed Fusion Process

Takafumi Ikeda,Toshi-Taka Ikeshoji,Makiko Yonehara,Minoru Hatate,Yasuhiko Otsubo,Kosuke Kuwabara,Tohru Nobuki,Hideki Kyogoku

doi:10.3390/cryst11050549

Takafumi Ikeda, Toshi-Taka Ikeshoji + Show 6 more

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https://doi.org/10.3390/cryst11050549

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Journal: Crystals	Publication Date: May 14, 2021
Citations: 18	License type: CC BY 4.0

Affiliation: Kindai University, Hitachi (Japan)

Abstract

Recently, high-entropy alloys (HEAs) have attracted much attention because of their superior properties, such as high strength and corrosion resistance. This study aimed to investigate the influences of process parameters on the microstructure and mechanical properties of CoCrFe NiTiMo HEAs using a laser-based powder bed fusion (LPBF) process. In terms of laser power and scan speed, a process map was constructed by evaluating the density and surface roughness of the as-built specimen to optimize the process parameters of the products. The mechanical properties of the as-built specimens fabricated at the optimum fabrication condition derived from the process map were evaluated. Consequently, the optimum laser power and scan speed could be obtained using the process map evaluated by density and surface roughness. The as-built specimen fabricated at the optimum fabrication condition presented a relative density of more than 99.8%. The microstructure of the as-built specimen exhibited anisotropy along the build direction. The tensile strength and elongation of the as-built specimen were around 1150 MPa and more than 20%, respectively.

Highlights

The influences of process parameters of laser-based powder bed fusion (LPBF) on the density and microstructure of CoCrFeNiTiMo high-entropy alloys (HEAs) were investigated experimentally, and the mechanical properties of the alloy fabricated at the optimum condition were evaluated
The width of a single track became narrower with decreasing laser power and increasing scan speed
The arithmetical mean height surface texture parameter (Sa) of the specimen fabricated at 300 W and 600 mm/s was 14.5 μm which was almost equal to that of Inconel 718 superalloy (IN718) [47]

Summary

Introduction

Additive manufacturing (AM), powder bed fusion (PBF), is extensively applied to manufacture complex-shaped products that are difficult to obtain using other metal processes in the aerospace and medical fields [1,2,3,4]. Metallic materials such as stainless steel, titanium alloys, Ni-based superalloys, and aluminum alloys have been widely utilized in AM fields [5]. These materials fabricated using the AM process have high strength, which is equivalent to the wrought materials. The development of high strength, high heat resistance, and high corrosion resistance alloys are required

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