Fabricating CoCrFeMnNi high entropy alloy via selective laser melting in-situ alloying

doi:10.1016/j.jmst.2020.01.002

Abstract

Abstract:

Quasi-equiatomic CoCrFeMnNi high entropy alloy (HEA) has been in-situ alloyed by selective laser melting (SLM) from a blend of CoCrFeNi pre-alloyed powder and Mn elemental powder. The blended powder shows good printability with various SLM parameters and the as-built HEA samples achieve a reliable forming quality. Despite the slight evaporation of Mn, energy dispersive spectrometer mapping and X-ray diffraction results show that the as-built HEA has a homogeneous chemical distribution and presents a single face-centred-cubic (fcc) phase, indicating successful in-situ alloying. The study has verified the feasibility of using blended powder to prepare high-quality HEA by SLM.

Key words: High entropy alloys, Laser processing, Selective laser melting, In-situ alloying, CoCrFeMnNi, Crystal structure

Peng Chen, Sheng Li, Yinghao Zhou, Ming Yan, Moataz M. Attallah. Fabricating CoCrFeMnNi high entropy alloy via selective laser melting in-situ alloying[J]. J. Mater. Sci. Technol., 2020, 43: 40-43.

Figures/Tables 5

Table 1 Chemical analysis and various properties of the raw materials used in this study.

Sample and property	Fe	Ni	Cr	Co	Mn
Pre-alloyed powder (at.%)	23.69	23.34	27.57	25.40	\
Blended powder (at.%)	18.59	18.31	21.64	19.93	21.53
SLM 259.3(at.%)	20.14	19.72	21.88	21.59	16.67
T_B (K)	3134	3003	2944	3200	2334
ΔH_vap (kJ/mol)	340	379	347	377	221
Atomic radius (pm)	126	124	128	125	127

Fig. 1. SEM images of (a) pre-alloyed CoCrFeNi powder, (b) Mn elemental powder and (c) blended powder and (d) as-built CoCrFeMnNi HEA blocks.

Fig. 2. (a) Dependence of density on the VED, with embedded SEM images of cross-section and (b) XRD results of the blended powder and as-built CoCrFeMnNi HEA samples; EDS mapping of (c) the SLM 120.4 and (d) the SLM 259.3.

Fig. 3. IPF maps of (a) the perpendicular plane and (b) the horizontal plane of the SLM 259.3 and (c) PF and IPF of the horizontal plane.

Table 2 Comparison of microhardness and tensile properties of CoCrFeMnNi HEAs fabricated by SLM using blended powder and pre-alloyed powder.

Materials	Microhardness (HV)	σ_uts (MPa)	ε_f (%)
Present blended powder	261 ± 7	681 ± 14	12.5 ± 0.5
Prealloyed powder [5]	/	609 ± 10	34 ± 3
Prealloyed powder [6]	/	601	35
Prealloyed powder [17]	212	/	/

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