AlSi12

metal

aluminium — hypoeutectic/eutectic Al-Si

AlSi12 AMAl-Si12A413 AM equivalentEN AC-44100 AMEOS AlSi12Scalmalloy alternative — castability grade

Density

2.67 g/cm³

YS (LPBF as-built (XY))

180–230 MPa

UTS (LPBF as-built (XY))

280–350 MPa

Elongation (LPBF as-built (XY))

3.0–8.0 %

Elastic modulus

70–76 GPa

Thermal conductivity

120.0–145.0 W/m·K

Composition — EN AC-44100 / ASTM A413 equivalent — Al-Si12 (12 wt% Si nominal)

Element	Min %	Max %	Notes
Al	—	—	balance — aluminium matrix
Si	11.00	13.500	12.6 wt% is the eutectic composition; Si content drives fluidity and sets thermal conductivity
Fe	—	0.550	Iron impurity; forms Al₃Fe intermetallics that can reduce ductility
Cu	—	0.050	Minimal copper content — not a precipitation-hardening alloy
Mg	—	0.100	Trace Mg only — insufficient for Mg₂Si precipitation hardening (contrast with AlSi10Mg which has ~0.3% Mg)

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Mechanical & thermal properties — 2 conditions

Property	LPBF as-built (XY)	LPBF stress-relieved 300°C/2h (XY)
Elastic modulus	70–76 GPa	72 GPa
Yield strength (0.2%)	180–230 MPa	130–175 MPa
Ultimate tensile strength	280–350 MPa	220–280 MPa
Elongation at break	3.0–8.0 %	5.0–12.0 %
Hardness (HV)	95–120 HV	75–95 HV
Density	2.67 g/cm³	2.67 g/cm³
Thermal conductivity	120.0–145.0 W/m·K	150.0–170.0 W/m·K
CTE	20.5 µm/m·K	—

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

Heat treatment decision: If maximum strength is required, specify as-built and DO NOT stress relieve. If dimensional stability, ductility, or thermal conductivity is the priority, specify 300°C/2h stress relief. A full anneal (>350°C) is rarely warranted — it reduces strength below die-cast equivalents.
Thermal conductivity optimisation: Stress-relieved AlSi12 (~160 W/m·K) outperforms stress-relieved AlSi10Mg (~150 W/m·K) due to higher Si content. For pure thermal management, AlSi12 is the better choice.
Porosity management: AlSi12's eutectic composition makes it one of the most process-tolerant Al alloys for LPBF. Still verify relative density >99% for pressure-tight components; hydrogen porosity from atmospheric moisture can occur if powder is not properly dried.
Comparison with AlSi10Mg: Choose AlSi12 when (1) castability/processability is paramount, (2) no heat treatment is planned, (3) thermal conductivity trumps strength. Choose AlSi10Mg when (1) highest as-built or T6-equivalent strength is needed, (2) the application involves sustained loads or fatigue.
Build orientation: Mechanical properties are anisotropic (Z-direction typically ~15–20% weaker than XY). Orient critical load paths in XY; verify Z-direction data for vertical features.
Surface quality: AlSi12 achieves good as-built surface roughness (Ra ~8–12 µm on vertical faces). For sealing surfaces or sliding fits, machining or abrasive finishing to Ra <3.2 µm is recommended.

Advantages

Eutectic composition gives near-zero solidification shrinkage — excellent dimensional accuracy and low porosity tendency vs hypoeutectic Al alloys
Best LPBF processability of the common Al-Si alloys — stable melt pool, low hot-cracking tendency
Higher thermal conductivity than AlSi10Mg in stress-relieved condition (~160 vs ~150 W/m·K) — preferred for pure thermal management applications
Good surface finish capability — suitable for complex thin-wall geometries
Well-established material for die-casting — AM AlSi12 can directly replace cast A413/EN AC-44100 components with design consolidation
No Mg requirement means less sensitivity to moisture-induced porosity vs AlSi10Mg

Limitations

Not precipitation-hardenable (no Mg for Mg₂Si precipitates) — as-built condition is peak strength; heat treatment only reduces strength
Lower strength than AlSi10Mg (~310 vs ~400–450 MPa UTS as-built) — not suitable where high specific strength is needed
Limited ductility in as-built condition (~5% elongation) — stress relief is recommended for any application involving cyclic loads or impact
Not a structural aerospace alloy — AlSi10Mg, Scalmalloy, or Ti-6Al-4V are preferred for aerospace structural applications
Moderate machinability — silicon particles cause tool wear; use carbide tooling with high cutting speeds
Limited post-AM heat treatment options vs AlSi10Mg (no T6 equivalent)

Typical applications

Automotive thermal management components (coolant manifolds, heat exchanger headers)Lighting brackets and housings requiring thin walls and good surface finishDie-cast replacement parts requiring near-net-shape geometry with AM complexityEnclosures and housings for electronics where thermal management is neededPrototype casting patterns and production-intent near-net-shape insertsLightweight structural brackets where thermal conductivity is secondary

AlSi12

Composition — EN AC-44100 / ASTM A413 equivalent — Al-Si12 (12 wt% Si nominal)

Mechanical & thermal properties — 2 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Compatible AM processes (2)

Other metal materials

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