Scalmalloy®

metal

aluminium alloy — Al-Mg-Sc-Zr

Al-Mg-ScAl-Mg-Sc-ZrAPWorks ScalmalloyScalmalloy RP

Density

2.67 g/cm³

YS (LPBF as-built (XY))

340–400 MPa

UTS (LPBF as-built (XY))

400–470 MPa

Elongation (LPBF as-built (XY))

12.0–20.0 %

Elastic modulus

68–74 GPa

Composition — APWorks EP2886242B1 (European Patent)

Element	Min %	Max %	Notes
Al	bal.		balance
Mg	4.00	4.900	Primary solid-solution strengthener
Sc	0.60	0.800	Nucleation agent; precipitates Al₃(Sc,Zr) dispersoids on ageing
Zr	0.20	0.500	Enhances coarsening resistance of Al₃Sc dispersoids; stabilises grain structure to higher temperatures
Mn	0.30	0.800	Solid-solution strengthening and corrosion resistance

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Mechanical & thermal properties — 3 conditions

Property	LPBF as-built (XY)	LPBF aged 325°C / 4h (XY) — primary service condition	LPBF aged 325°C / 4h (Z)
Elastic modulus	68–74 GPa	—	—
Yield strength (0.2%)	340–400 MPa	440–520 MPa	410–485 MPa
Ultimate tensile strength	400–470 MPa	480–560 MPa	460–540 MPa
Elongation at break	12.0–20.0 %	9.0–17.0 %	8.0–16.0 %
Hardness (HV)	—	140–170 HV10	—
Fatigue strength	—	155–215 MPa	—
Density	2.67 g/cm³	—	—
Relative density	99.0–99.9 %	—	—
CTE	16.0–17.5 µm/m·K	—	—
As-built surface Ra	7.0–18.0 µm	—	—

Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.

Engineering considerations

Ageing is mandatory for structural use: 325°C / 4h. This can be performed on parts still attached to the build plate to relieve residual stress simultaneously. Do not exceed 350°C or 6h — dispersoid coarsening rapidly degrades properties.
No solution treatment required — unlike conventional precipitation-hardened Al alloys (6000, 7000 series). The LPBF rapid solidification traps Sc/Zr in supersaturated solid solution, so ageing directly is sufficient.
Parameter development: Scalmalloy is more tolerant of VED variation than AlSi10Mg. However, oxygen in powder or build atmosphere causes preferential Sc oxidation — maintain O₂ < 500 ppm, ideally < 200 ppm.
Fatigue design: use machined-surface fatigue data (not as-built) for design calculations. As-built surface Ra 10–18 µm reduces fatigue limit by ~50% vs. machined. Vibratory finishing or electropolishing recommended for fatigue-critical surfaces.
Powder reuse: limited data on Scalmalloy powder reuse. Treat as sensitive to oxygen pick-up. Characterise each reuse lot to ASTM F3049. APWorks recommends ≤10 reuse cycles.
Cost justification: cost per kg is very high. Use in topology-optimised designs where the mass savings (vs. AlSi10Mg or Ti-6Al-4V) and fatigue performance justify the material cost premium. Typical application: aerospace bracket where Ti-6Al-4V is over-specified but AlSi10Mg fails fatigue.
Corrosion protection: Scalmalloy has inherently better corrosion resistance than Al-Si alloys but standard aerospace coatings (anodising, chromate conversion, primer) should still be applied for corrosive environments.

Advantages

Highest strength-to-density ratio of any commercial LPBF aluminium alloy — ~30–40% stronger than AlSi10Mg at same density
Excellent fatigue resistance — far superior to Al-Si alloys due to equiaxed microstructure and absence of brittle Si eutectic
Low anisotropy — equiaxed grains from Sc nucleation reduce XY/Z strength difference to <8%
Good weldability and compatibility with conventional Al fabrication methods for hybrid structures
Simple ageing cycle: 325°C / 4h in air — no complex solution treatment or quench required
Superior corrosion resistance vs. Al-Si alloys — high Mg content forms protective oxide; no Si-phase galvanic cells
No hot-cracking — Sc grain refinement eliminates the solidification cracking susceptibility of high-Mg Al alloys

Limitations

High cost — Scalmalloy powder is 10–20× more expensive than AlSi10Mg due to Sc content (Sc is a rare earth element at ~$2,000/kg)
Proprietary alloy — APWorks/Airbus holds patents; limited powder supplier competition constrains pricing
No published ASTM or ISO material specification — qualification cost is higher than for standardised alloys
Maximum service temperature ~150°C — Al₃(Sc,Zr) dispersoids coarsen rapidly above 300°C
Parameter sensitivity — LPBF parameters must be optimised for each machine; green laser may offer advantages (not yet widely validated)
Limited creep resistance — not suitable for high-temperature structural applications
Ageing temperature must be controlled ±10°C to avoid under- or over-ageing

Typical applications

Aerospace structural brackets and secondary structure — typical design goal: equivalent strength to AlSi10Mg at 25% less materialUAV (drone) frames, motor mounts, and structural componentsSatellite structures and optical instrument mountsHigh-performance motorsport suspension components and gearbox bracketsLightweight structural topology-optimised parts where fatigue governs designDefence unmanned systems and lightweight weapon system mountsHeat exchangers where high specific strength and thermal cycling resistance matter

Standards & certifications

ASTM-F3318established

Wrought Al specification referenced for comparison — no dedicated AM Scalmalloy standard exists yet

aerospace

No ASTM or ISO AM standard specifically for Scalmalloy. Aerospace qualification follows OEM-specific qualification plans using ASTM F3122 as framework.

AMS-7000established

LPBF process requirements for aerospace parts

aerospacedefence

Scalmalloy®

Composition — APWorks EP2886242B1 (European Patent)

Mechanical & thermal properties — 3 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Standards & certifications

Compatible AM processes (1)

Other metal materials

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