Damage tolerant aluminium material having a layered microstructure

1. A method of producing a wrought aluminium material, comprising the steps:

producing a cast aluminium material of a precipitation hardenable aluminium alloy, wherein the precipitation hardenable aluminium alloy consists of, in wt %:

0.3-1.5 Si,

0.3-1.5 Mg,

≤0.3 Mn,

<0.5 Cu,

<0.5 Fe,

<0.3 Nb,

<0.3 V,

<0.3 Cr,

<0.2 Zn,

<0.2 Ti,

<0.2 Mo,

<0.2 Zr, and

unavoidable impurities each 0.05 wt. % maximum and the total of impurities 0.15 wt. % maximum, and

balance aluminium,

wherein the cast material further comprises grains, dendrites or cells having a two-zone cast structure with two distinct zones including a first centre zone enriched in elements capable of reacting peritectically with aluminium and a second zone, surrounding the first zone, enriched in elements capable of reacting eutectically with aluminium, the first zone occupying 20-50% of the total volume measured on the cross section as peritectic hills in the interference contrast in LOM,

wherein the precipitation hardenable aluminium alloy comprises peritectic alloying elements with a combined partition coefficient Σk of above 3 and a proportion of peritectic elements of more than 0.02×[wt % eutectic alloying elements] able to suppress the local eutectic element content in the peritectic zone to <0.8×[the average eutectic alloying elements content of the alloy in wt %], and

wherein the precipitation hardenable aluminium alloy is cast while controlling the casting speed so as to produce the two-zone cast structure, wherein the solidification time during casting is controlled to at least 75 seconds;

optionally homogenising the cast material with the two-zone cast structure at homogenization conditions that preserve the two distinct zones of the cast material;

optionally preheating the billet;

deforming the cast structure to produce a material with a layered structure comprising alternate layers of different mechanical properties;

cooling said material; and

optionally heat treating said material.

2. The method according to claim 1 , where the material is deformed by extrusion or forging.

3. The method according to claim 1 , wherein the combined partition coefficient Σk is above 5.

4. The method according to claim 3 , wherein the combined partition coefficient Σk is above 8.

5. The method according to claim 1 , wherein the Mg/Si ratio of the precipitation hardenable aluminium alloy is >1.

6. A method of producing a wrought aluminium material, comprising the steps:

producing a cast aluminium material of a precipitation hardenable aluminium alloy, wherein the precipitation hardenable aluminium alloy consists of, in wt %:

0.3-1.5 Si,

0.3-1.5 Mg,

≤0.3 Mn,

<0.5 Cu,

<0.5 Fe,

<0.3 Nb,

<0.3 V,

<0.3 Cr,

<0.2 Zn,

<0.2 Ti,

<0.2 Mo,

<0.2 Zr, and

unavoidable impurities each 0.05 wt. % maximum and the total of impurities 0.15 wt. % maximum, and

balance aluminium,

wherein the cast material further comprises grains, dendrites or cells having a two-zone cast structure with two distinct zones including a first centre zone enriched in elements capable of reacting peritectically with aluminium and a second zone, surrounding the first zone, enriched in elements capable of reacting eutectically with aluminium, the first zone occupying 20-50% of the total volume measured on the cross section as peritectic hills in the interference contrast in LOM,

wherein the precipitation hardenable aluminium alloy comprises peritectic alloying elements with a combined partition coefficient Σk of above 3 and a proportion of peritectic elements of more than 0.02×[wt % eutectic alloying elements] able to suppress the local eutectic element content in the peritectic zone to <0.8×[the average eutectic alloying elements content of the alloy in wt %], and

wherein the precipitation hardenable aluminium alloy is cast while controlling the casting speed so as to produce the two-zone cast structure, and wherein the solidification time during casting is controlled to at least 75 seconds;

optionally preheating the cast material comprising the two-zone cast structure;

deforming the cast material comprising the two-zone cast structure to produce a material with a layered structure comprising alternate layers of different mechanical properties;

cooling said material; and

optionally heat treating said material.