Synthesis, microstructural evolution, and compaction behavior of Mg30-Al25-Ti25-Li15-Si5 lightweight high-entropy alloys synthesized via mechanical alloying

Ammar, Hany R.; Sivasankaran, Subbarayan; Al-Mufadi, Fahad A.

doi:10.2478/msp-2025-0014

Figures & Tables

Surface morphology of as-received elemental powders used to synthesize LWHEA in this work by SEM: (a) Mg, (b) Al, (c) Ti, and (d) Si.

SEM images of the microstructures of MAed Mg30-Al25-Ti25-Li15-Si5 LWHEAs milled for different times (5, 15, and 20 h) showing powder surface morphology: (a) L1-5 h, (b) L1-10 h, and (c) L1-20 h.

SEM images of the microstructures with EDAX analyses of MAed Mg30-Al25-Ti25-Li15-Si5 LWHEAs milled for different times (5, 15, and 20 h) showing element composition (both wt% and at%): (a) L1-5 h, (b) L1-10 h, and (c) L1-20 h.

SEM images of the microstructures with elemental mapping of MAed Mg30-Al25-Ti25-Li15-Si5 LWHEAs milled for different times (5, 15, and 20 h) showing the distribution of the incorporated elements and alloy formation (first from left image: SE SEM microstructure; immediate right of four images: mapping of Mg, Al, Ti, and Si): (a) L1-5 h, (b) L1-10 h, and (c) L1-20 h.

XRD peaks of the as-received elemental powders of (a) Mg, (b) Al, (c) Ti, (d) Li, and (e) Si.

XRD patterns of the milled Mg30-Al25-Ti25-Li15-Si5 LWHEA powders for different durations: (a) L1-0 h, (b) L1-5 h, (c) L1-10 h, and (d) L1-20 h samples.

Scherrer model: (a) Mg30-Al25-Ti25-Li15-Si5 (0 h), (b) Mg30-Al25-Ti25-Li15-Si5 (5 h), (c) Mg30-Al25-Ti25-Li15-Si5 (10 h), and (d) Mg30-Al25-Ti25-Li15-Si5 (20 h).

W-H UDM: (a) Mg30-Al25-Ti25-Li15-Si5 (0 h), (b) Mg30-Al25-Ti25-Li15-Si5 (5 h), (c) Mg30-Al25-Ti25-Li15-Si5 (10 h), and (d) Mg30-Al25-Ti25-Li15-Si5 (20 h).

W-H USDM: (a) Mg30-Al25-Ti25-Li15-Si5 (0 h), (b) Mg30-Al25-Ti25-Li15-Si5 (5 h), (c) Mg30-Al25-Ti25-Li15-Si5 (10 h), and (d) Mg30-Al25-Ti25-Li15-Si5 (20 h).

SSP model: (a) Mg30-Al25-Ti25-Li15-Si5 (0 h), (b) Mg30-Al25-Ti25-Li15-Si5 (5 h), (c) Mg30-Al25-Ti25-Li15-Si5 (10 h), and (d) Mg30-Al25-Ti25-Li15-Si5 (20 h).

Structural properties of Mg30-Al25-Ti25-Li15-Si5 (0, 5, 10, and 20 h) nanocomposite powders milled at different durations: (a) dislocation density, (b) excess free volume, (c) SFP, and (d) N–R parameter.

HRTEM analysis of MAed LWHEA powders for different milled duration times: (a1–a4) BFI, (b1–b4) DFI, and (c1–c4) SAED.

HRTEM – elemental mapping and EDS analyses of the Mg30-Al25-Ti25-Li15-Si5 (20 h) LWHEA powder samples.

HRTEM – lattice fringes of the Mg30-Al25-Ti25-Li15-Si5 LWHEA powder samples: (a) Mg30-Al25-Ti25-Li15-Si5 0 h, (b) Mg30-Al25-Ti25-Li15-Si5 – 5 h, (c) Mg30-Al25-Ti25-Li15-Si5 10 h, and (d) Mg30-Al25-Ti25-Li15-Si5 – 20 h lattice fringes correspond to (2 0 0).

Compaction behavior of Mg30-Al25-Ti25-Li15-Si5 LWHEAs milled for different times (0, 5, 15, and 20 h) showing the behavior at various stages: (a) cold compaction at RT; (b) hot compaction at 275°C; and (c) hot compaction at 550°C.

A list of low-density elements selected for the present study [14]_

Element	Atomic number	Atomic radius (nm)	Melting temperature (K)	Density (g/cm³)
Mg	24	0.1249	923	1.74
Al	26	0.1241	933.3	2.70
Ti	13	0.1432	1,941	4.50
Li	27	0.1251	453.5	0.53
Si	14	0.1153	1,687	2.33

Chemical composition of the developed Mg30-Al25-Ti25-Li15-Si5 LWHEA_

Mg	Al		Ti		Li		Si
Wt%	At%	Wt%	At%	Wt%	At%	Wt%	At%	Wt%	At%
30	24.57	25	18.45	25	10.40	15	43.03	5	3.55

Variation in relative density in different stages during compaction (both cold and hot compaction) as a function of compaction pressure and temperature for Mg30-Al25-Ti25-Li15-Si5 LWHEAs milled for different times (0, 5, 15, and 20 h)_

Sample	T (°C)	P (MPa)	Compaction stages	RD (%)	Sample	T (°C)	P (MPa)	Compaction stages	RD (%)
L1-0 h	RT	20	Particle rearrangement stage	56.81	L1-5 h	RT	20	Particle rearrangement stage	55.85
		30		61.55			30		60.43
		40		65.56			40		64.30
		50		68.97			50		67.57
		60	Elastic deformation stage	71.95			60	Elastic deformation stage	70.42
		70		74.71			70		73.07
		80		77.15			80		75.40
		90		79.55			90		77.69
		100		81.70			100		79.74
		125	Plastic deformation stage	86.38			125	Plastic deformation stage	84.19
		150		90.38			150		87.98
		175		94.22			175		91.62
		200		97.40			200		94.63
	275	20	Particle rearrangement stage	61.26		275	20	Particle rearrangement stage	60.43
		30		65.34			30		64.39
		40		68.67			40		67.62
		50		71.68			50		70.54
		60	Elastic deformation stage	74.34			60	Elastic deformation stage	73.11
		70		76.80			70		75.49
		80		78.83			80		77.45
		90		80.85			90		79.40
		100		82.66			100		81.15
		125	Plastic deformation stage	87.05			125	Plastic deformation stage	85.38
		150		91.17			150		89.33
		175		94.90			175		92.91
		200		98.36			200		96.22
	550	20	Particle rearrangement stage	69.04		550	20	Particle rearrangement stage	68.47
		30		72.42			30		71.80
		40		75.13			40		74.46
		50		77.51			50		76.79
		60	Elastic deformation stage	79.73			60	Elastic deformation stage	78.98
		70		81.79			70		81.00
		80		83.56			80		82.72
		90		85.26			90		84.51
		100		86.93			100		86.03
		125	Plastic deformation stage	90.48			125	Plastic deformation stage	89.64
		150		93.82			150		92.77
		175		96.82			175		95.71
		200		99.67			200		98.48
L1-10 h	RT	20	Particle Rearrangement stage	54.22	L1-20 h	RT	20	Particle Rearrangement stage	52.33
		30		58.62			30		56.33
		40		62.25			40		59.67
		50		65.31			50		62.48
		60	Elastic deformation stage	67.97			60	Elastic deformation stage	64.92
		70		70.43			70		67.16
		80		72.59			80		69.12
		90		74.72			90		71.04
		100		76.61			100		72.75
		125	Plastic deformation stage	80.71			125	Plastic deformation stage	76.44
		150		84.19			150		79.55
		175		87.52			175		82.51
		200		90.25			200		84.94
	275	20	Particle rearrangement stage	59.40	L1-20 h	275	20	Particle rearrangement stage	57.80
		30		63.22			30		61.41
		40		66.34			40		64.35
		50		69.14			50		66.98
		60	Elastic deformation stage	71.61			60	Elastic deformation stage	69.29
		70		73.89			70		71.43
		80		75.77			80		73.18
		90		77.64			90		74.92
		100		79.30			100		76.47
		125	Plastic deformation stage	83.34			125	Plastic deformation stage	80.22
		150		87.11			150		83.70
		175		90.50			175		86.83
		200		93.64			200		89.72
	550	20	Particle rearrangement stage	69.97	L1-20 h	550	20	Particle rearrangement stage	68.88
		30		72.89			30		71.71
		40		75.29			40		74.03
		50		77.39			50		76.06
		60	Elastic deformation stage	79.33			60	Elastic deformation stage	77.94
		70		80.97			70		79.52
		80		82.58			80		81.07
		90		84.06			90		82.50
		100		85.47			100		83.85
		125	Plastic deformation stage	88.66			125	Plastic deformation stage	86.92
		150		91.46			150		89.61
		175		94.06			175		92.10
		200		96.48			200		94.42

Estimation of the size and strain for different milled time durations of Mg30-Al25-Ti25-Li15-Si5 LWHEA powders_

Sample/model	Parameter	Mg₃₀-Al₂₅-Ti₂₅-Li₁₅-Si₅ (0 h)	Mg₃₀-Al₂₅-Ti₂₅-Li₁₅-Si₅ (5 h)	Mg₃₀-Al₂₅-Ti₂₅-Li₁₅-Si₅ (10 h)	Mg₃₀-Al₂₅-Ti₂₅-Li₁₅-Si₅ (20 h)
Scherrer	Size (D) (nm)	1422.14	1066.7100	719.3300	618.4100
W-H UDM	Size (D) (nm)	90.5700	89.0300	81.3200	73.7200
W-H UDM	Strain (ε) (%)	0.0002	0.0013	0.0044	0.0097
W-H USDM	Size (D) (nm)	47.0200	44.5000	34.5800	30.8000
W-H USDM	Strain (ε) (%)	0.0004	0.0011	0.0032	0.0043
SSP	Size (D) (nm)	98.0400	60.2200	54.1900	42.5300
SSP	Strain (ε) (%)	0.0001	0.0008	0.0010	0.0030

Properties of the elements used in the present study to develop the Mg30-Al25-Ti25-Li15-Si5 alloy_

Element	Atomic number	Atomic radius (nm)	Pauling electronegativity	VEC	Atomic weight	Melting temperature (K)	Density (g/cm³)
Mg	24	0.1249	1.660	6	51.9961	2,180	7.2
Al	26	0.1241	1.833	8	55.8450	1,811	7.9
Ti	13	0.1432	1.610	3	26.9815	933	2.7
Li	27	0.1251	1.880	9	58.9332	1,768	8.9
Si	14	0.1153	1.900	4	28.0855	1,687	2.3

Enthalpy of mixing ( H mix AB {H}_{\text{mix}}^{\text{AB}} ) between each pair of elements in the Mg30-Al25-Ti25-Li15-Si5 developed alloy_

Element	Mg	Al	Ti	Li	Si
Mg	Mg	−2	16	0	−26
Al	−2	Al	−30	−4	−19
Ti	16	−30	Ti	34	−66
Li	0	−4	34	Li	−30
Si	−26	−19	−66	−30	Si

Physicochemical and thermodynamic properties for the Mg30-Al25-Ti25-Li15-Si5 developed alloy powders via MA_

Alloy code	Mixing enthalpy, ΔH _mix (kJ/mol)	Entropy of mixing, ΔS _mix (J/mol K)	Gibbs free energy, Δ G mix \text{Δ}{G}_{\text{mix}} (J/mol)	Melting temperature, T _m (K)	Thermodynamic parameter, Ω	Mean atomic radius, r ¯ \bar{r} (nm)	Atomic size difference, δ (%)	Valency electron concentration, VEC	Difference in Pauling electronegativity, Δ X \text{Δ}X	Density, ρ (g/cm³)
L1-0, L1-5, L1-10, and L1-20	−0.4205	11.42	−3,823	855.8	15.82	0.1504	5.93%	−0.4205	11.42	1.704

Ball milling processing parameters of the developed Mg30-Al25-Ti25-Li15-Si5 LWHEA_

Alloy code	Chemical composition	PBR	Milling speed	Milling time (h)
L1-0	Mg₃₀-Al₂₅-Ti₂₅-Li₁₅-Si₅	15:1	300 rpm	0 (premixed Conditions)
L1-5				5
L1-10				10
L1-20				20

Synthesis, microstructural evolution, and compaction behavior of Mg30-Al25-Ti25-Li15-Si5 lightweight high-entropy alloys synthesized via mechanical alloying

Figures & Tables

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A list of low-density elements selected for the present study [14]_

Chemical composition of the developed Mg30-Al25-Ti25-Li15-Si5 LWHEA_

Variation in relative density in different stages during compaction (both cold and hot compaction) as a function of compaction pressure and temperature for Mg30-Al25-Ti25-Li15-Si5 LWHEAs milled for different times (0, 5, 15, and 20 h)_

Estimation of the size and strain for different milled time durations of Mg30-Al25-Ti25-Li15-Si5 LWHEA powders_

Properties of the elements used in the present study to develop the Mg30-Al25-Ti25-Li15-Si5 alloy_

Enthalpy of mixing ( H mix AB {H}_{\text{mix}}^{\text{AB}} ) between each pair of elements in the Mg30-Al25-Ti25-Li15-Si5 developed alloy_

Physicochemical and thermodynamic properties for the Mg30-Al25-Ti25-Li15-Si5 developed alloy powders via MA_

Ball milling processing parameters of the developed Mg30-Al25-Ti25-Li15-Si5 LWHEA_

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