A Novel Low-Density, High-Hardness, High-entropy Alloy with Close-packed Single-phase Nanocrystalline Structures

Figures & data

Table 1. Data from literature to calculate Ω and δ.[2,11]

		Al	Li	Mg	Sc	Ti
r (nm)		0.14317	0.15194	0.16013	0.16410	0.14615
Tm (K)		933	454	922	1814	1943
ΔH^mix (kJ mol^−1)	Li	−4
	Mg	−2	0
	Sc	−38	12	−3
	Ti	−30	34	16	8

Figure 1. XRD pattern of as-milled alloy.

Figure 2. XRD pattern of uncontaminated alloy after annealing at 500°C.

Figure 3. (a) Bright field TEM image and diffraction pattern, (b) dark field image, and (c) grain size distribution of as-milled uncontaminated material.

Table 2. Properties of alloys prepared.

Alloy	Annealing temp. (°C)	Crystal structure	X-ray grain size (nm)	Hardness (GPa)
Al20Li20Mg10Sc20Ti30	as milled	fcc	12	5.8
	500	hcp	26	4.9
Al20Li20Mg10Sc20Ti30 w/ N, O	as milled	fcc	12	6.1
	500	fcc^a	nc^a	5.9
	800	fcc^a	nc^a	5.75

^aThe N, O-containing alloys exhibited slight phase separation or distortion upon annealing resulting in a structure similar to fcc. Because the diffraction peaks are split, measurement of the grain size by line profile analysis is inaccurate, but the broadness of the peaks indicates a nanocrystalline structure.

Figure 4. Ashby plot of strength vs. density for engineering materials. (Yield strength for metals and polymers, tear strength for elastomers, compressive strength for ceramics,[19] and tensile strength for composites.) Reproduced with permission from Elsevier 2010.[20]

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