Microstructural Characterization of TiC-Reinforced Metal Matrix Composites Fabricated by Laser Cladding Using FeCrCoNiAlTiC High Entropy Alloy Powder

Sangwoo Nam,Hyung Won Lee,In-Ho Jung,Young-Min Kim

doi:10.3390/app11146580

Sangwoo Nam, Hyung Won Lee + Show 2 more

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https://doi.org/10.3390/app11146580

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Abstract

TiC-reinforced metal matrix composites were fabricated by laser cladding and FeCrCoNiAlTiC high entropy alloy powder. The heat of the laser formed a TiC phase, which was consistent with the thermodynamic calculation, and produced a coating layer without interfacial defects. TiC reinforcing particles exhibited various morphologies, such as spherical, blocky, and dendritic particles, depending on the heat input and coating depth. A dendritic morphology is observed in the lower part of the coating layer near the AISI 304 substrate, where heat is rapidly transferred. Low heat input leads to an inhomogeneous microstructure and coating depth due to the poor fluidity of molten pool. On the other hand, high heat input dissolved reinforcing particles by dilution with the substrate. The coating layer under the effective heat input of 50 J/mm2 had relatively homogeneous blocky particles of several micrometers in size. The micro-hardness value of the coating layer is over 900 HV, and the nano-hardness of the reinforcing particles and the matrix were 17 GPa and 10 GPa, respectively.

Highlights

High entropy alloys (HEAs), which are solid solution alloys with five or more elements, maintain a relatively simple phase due to high configurational entropy [1,2]
The outstanding mechanical and high thermal properties of HEAs are expected to be applied to various structural materials such as tools, dies, molds, and furnace materials
When using FeCrCoNiAlTiC powder, it was necessary to confirm whether titanium carbide was a thermodynamically stable carbide in the in situ reaction

Summary

Introduction

High entropy alloys (HEAs), which are solid solution alloys with five or more elements, maintain a relatively simple phase due to high configurational entropy [1,2]. The outstanding mechanical and high thermal properties of HEAs are expected to be applied to various structural materials such as tools, dies, molds, and furnace materials. On the other hand, when HEAs are used as a coating material, less amount of HEAs could be used cost-effectively and provides functionality to the surface [4]. When Ti is added to the face-centered-cubic (FCC) HEAs, bodycentered-cubic (BCC) HEAs, which have higher hardness and wear performance due to the cocktail effect, are formed [5]. TiC is one of the most used reinforcing materials due to its high mechanical properties, chemical stability, and good wettability with Co, Ni, and Fe-based alloys [6]. The use of Ti is expected to form TiC phase and strengthen the matrix, resulting in an excellent metal matrix composite (MMC)

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