Filling the white spots on the aluminium map
The choice engineers never wanted to make
Aluminium alloys are sorted into series (2xxx, 5xxx, 6xxx, 7xxx), and each series is boxed in by specified limits on its chemistry. Those limits also establish its character. The 5xxx family (aluminium–magnesium) forms beautifully and resists corrosion, but it isn't particularly strong. The 7xxx family (aluminium–zinc–magnesium–copper) is very strong, but hard to form, trickier to weld, and more prone to corrosion. For decades, choosing an alloy meant choosing which weakness you could live with.
A different question
CrossAlloy.57 starts from a simple provocation: what if an alloy didn't have to stay inside those boxes at all? Picture the alloy families as regions on a map. The standard alloys sit deep inside their own territories. Between them lie large white spots: compositions nobody designs for because they fall between the official classes. CrossAlloy.57 is built to live in one of those white spots on purpose.
What it is
CrossAlloy.57 is a 5xxx / 7xxx aluminium crossover alloy: an AlMgZn(Cu) composition engineered so that 5xxx-style formability and 7xxx-style strength are available together, rather than one at the expense of the other.
Key benefits at a glance
- Excellent suitability for complex lightweight structures : Enables demanding component designs with high structural performance.
- High mechanical performance : Stable T-phase strengthening allows medium to high strength levels, depending on the heat treatment.
- Good corrosion resistance : Including good resistance to intergranular corrosion and stress-corrosion cracking.
- High fatigue resistance : Comparable to or better than established 7xxx and 2xxx aerospace aluminium alloys.
- Good weldability : RSW, MIG, TIG, FSW and laser welding successfully tested for different requirements.
- Fine-grained microstructure : Uniform forming behavior, low orientation dependency and good processability, incl. superplastic and hot forming.
- Cryogenic performance : Strong indications for exceptional performance at cryogenic temperature.
- High radiation resistance : Strengthening precipitates remain stable under strong ion irradiation, resistant up to 2 dpa.
- Potential for more sustainable high-performance applications : Improved scrap availability supports future-oriented material concepts.
Why it works
The trick is how the alloy hardens. A classic 7xxx alloy like 7075 gets its peak strength from one specific precipitate (the η-phase). CrossAlloy.57 keeps a high magnesium content like a 5xxx alloy, which nudges it to harden through a different precipitate instead: the T-phase. That one change lets it hold on to the good ductility of a high-magnesium alloy while still gaining real, heat-treatable strength. In AMAG's own testing it also shows better corrosion resistance and weldability than conventional 7xxx alloys at similar strength.
Simplified composition (why it sits between the two)
| Alloy | % Mg | % Zn | % Cu | Class | Hardening precipitate |
|---|---|---|---|---|---|
| EN AW-5182 | 4.5 | < 0.25 | < 0.15 | non-heat-treatable | none |
| EN AW-7075 | 2.5 | 5.6 | 1.6 | heat-treatable | η-phase (MgZn₂) |
| CrossAlloy.57 | 4.5 | 3.5 | 0.5 | heat-treatable | T-phase (Mg₃₂(Al,Zn)₄₉) |
A property mix in between
The result is not "best at everything". It is a material that deliberately sits between its two parents, matching neither one's single strongest trait but sidestepping both of their worst weaknesses.
| Property | 5xxx | 7xxx | CrossAlloy.57 |
|---|---|---|---|
| Strength | ~ | +++ | ++(+) |
| Formability | +++ | – | ++ |
| Bendability | ++ | ––– | ~ |
| Elongation | ++ | – | + |
| Corrosion resistance | +++ | –– | + |
| Weldability | +++ | +/–– | ++ |
| Adhesive bonding | +++ | n.a. | +++ |
| Recyclability | ++ | – | +/– |
Qualitative assessment, not a standardized test scale. Note that not all property combinations are achievable in each temper.
Shape it many ways
CrossAlloy.57 isn't tied to a single manufacturing route. Four have been demonstrated, each suited to different geometries and volumes.
| Route | Character | Target strength (Rp0.2) |
|---|---|---|
| Cold forming | room temperature, fast, low shape complexity | > 350 MPa |
| Superplastic forming (SPF) | high temperature, slow, most complex shapes | > 360 MPa |
| Hot-form quenching (HFQ) | high temperature, fast, strong hardening | > 370 MPa |
| Machining | room temperature, high precision, minimal distortion, no hot spots | > 440 MPa |
From a 100-gram sample to industrial production
CrossAlloy.57 didn't start as a product; it earned its way to one. It began as 100-gram lab samples that first revealed the unusual strength-plus-formability behavior. Scaling to 1,000-gram batches made clear that processing a crossover composition at larger scale is considerably harder than for a standard alloy: it took focused R&D and numerous processing trials before the first industrial production trial succeeded at AMAG's own plant in Ranshofen. Further trials, backed by early partner commitment, produced the first prototype parts. In other words: this is a real, industrially produced alloy, not a paper concept.
Where it's being explored today
CrossAlloy.57's specific property mix opens doors across several potential applications, which were identified by extensive market research and cross-correlation with available material data. Each application page carries the actual data: what is measured, and what is still uncertain or needs to be assessed.
Go deeper
Explore the application area that fits your problem, or read the metallurgy behind the alloy.