Realizing superior strength-ductility combination in dual-phase AlFeCoNiV high-entropy alloy through composition and microstructure design

Figures & data

Figure 1. (a) DSC heating and cooling curves, (b) XRD patterns of as-cast (1#) and homogenized (2#) Al025 HEAs; (c)–(f) grain orientation map, EDS maps, phase distribution map and bright-field (BF) image with selected area electron diffraction (SAED) pattern of 1# Al025 HEA; (g)–(l) grain orientation map, EDS maps, phase distribution map and BF image with SAED pattern, dark-field (DF) image corresponding to superlattice spot (100) of L1₂ phase, BF image and SAED pattern along B2 phase [001] zone axis of 2# Al025 HEA.

Table 1. Chemical composition (at. %) of these HEAs as determined by SEM/TEM-EDS analysis.

Alloy	Samples	Phase	Al	Fe	Co	Ni	V
Al025FeCoNiV	As-cast (1#)	Overall	5.80	23.40	23.80	23.00	24.00
		FCC	5.50	24.60	24.40	23.70	21.80
		BCC	7.50	22.70	22.50	18.60	28.80
	Homogenized	L12	4.30	24.30	23.90	23.70	23.80
	(2#)	B2	13.50	20.60	23.30	18.30	24.30
	3#	FCC	3.62	26.38	23.68	23.09	23.23
		BCC	15.95	21.76	23.43	15.47	23.38
	4#	L12	3.62	26.38	23.68	23.09	23.23
		B2	15.95	21.76	23.43	15.47	23.38

Figure 2. (a) SXRD patterns of recrystallized (3#) and annealed states (4#) Al025 HEAs; (b)–(d) grain orientation map, phase distribution map and EDS maps of Al025 HEA recrystallized at 900°C for 1.5 h (3#); (e) Euler distribution map and phase distribution map of Al025 HEA recrystallized at 800°C for 10 h; (f) BF image with SAED pattern of 3# Al025 HEA; (g)–(l) BF image. DF image corresponding to (100) of L1₂ phase with SAED pattern along L1₂ [001] zone axis, TEM-EDS maps of L1₂ region, BF image with SAED pattern along B2 [001] zone axis, TEM-EDS maps of B2 region and EDS composition profiles across B2 phase of 4# Al025 HEA.

Figure 3. (a) Tensile engineering stress–strain curves, (b) comparison of the mechanical properties of Al025 HEA with those of existing dual-phase HEAs, (c) strain-hardening rate curves, (d) SEM images of the fracture surfaces of 4# Al025 HEA.

Table 2. YS, UTS, and uniform strain (US) of Al025 HEAs.

Alloy	YS (MPa)	UTS (MPa)	US (%)
1#	510	1045	30
2#	420	1161	25
3#	1087	1430	25
4#	1098	1530	19

Figure 4. (a)–(c) Grain orientation map, phase map, and KAM map of 4# Al025 HEA subjected to strain of 12%; (d)–(f) BF image along L12 [011] zone axis of 4# sample; (g)–(i) Schematic of the recrystallization and deformation processes in 4# Al025 HEA.