Aluminum alloy foam and method of manufacturing the same

1. Aluminum (Al) alloy foam comprising:

an Al alloy matrix containing magnesium (Mg); and

hollow ceramic spheres dispersed in the Al alloy matrix,

wherein a reaction layer comprising a Mg—Al composite oxide is formed at an interface where the Al alloy matrix is in contact with the hollow ceramic spheres.

2. The Al alloy foam of claim 1 , wherein a density of the Al alloy foam is higher at a surface region of the Al alloy foam compared to a middle region of the Al alloy foam.

3. The Al alloy foam of claim 1 , wherein a hardness of the Al alloy foam is higher at a surface region of the Al alloy foam compared to a middle region of the Al alloy foam.

4. The Al alloy foam of claim 1 , wherein an aspect ratio between a major width and a minor width of the hollow ceramic spheres is greater at a surface region of the Al alloy foam compared to a middle region of the Al alloy foam.

5. The Al alloy foam of claim 1 , wherein a content of Mg is 2.0 wt % to 8.0 wt %.

6. The Al alloy foam of claim 1 , wherein the hollow ceramic spheres have a particle size ranging from 125 μm to 500 μm, and

wherein a content of the hollow ceramic spheres is 20 Vol. % to 50 Vol. %.

7. The Al alloy foam of claim 1 , wherein the Al alloy matrix further contains silicon (Si), and

wherein a content of Si in the Al alloy matrix is less than 1.0 wt %.

8. The Al alloy foam of claim 1 , wherein a dispersion uniformity (%) of the hollow ceramic spheres dispersed in the Al alloy matrix is defined as shown in Equation 1 and is 82% to 96%.

Dispersion uniformity (%)={1−(Standard deviation of fraction of hollow ceramic spheres/Average fraction of hollow ceramic spheres)}×100  [Equation 1]

9. A method of manufacturing aluminum (Al) alloy foam, the method comprising:

providing first Al alloy foam comprising an Al alloy matrix containing magnesium (Mg), and hollow ceramic spheres dispersed in the Al alloy matrix, wherein a reaction layer comprising a Mg—Al composite oxide is formed at an interface where the Al alloy matrix is in contact with the hollow ceramic spheres; and

forming second Al alloy foam by rolling the first Al alloy foam while the first Al alloy foam is being heated in such a manner that a surface region of the first Al alloy foam is higher in temperature than a middle region of the first Al alloy foam.

10. The method of claim 9 , wherein the forming of the second Al alloy foam comprises rolling the first Al alloy foam while the first Al alloy foam is being heated to a solid-liquid coexistence temperature of the Al alloy matrix.

11. The method of claim 9 , wherein the first Al alloy foam comprises Mg: 2.0 wt % to 8.0 wt %, silicon (Si): 0 wt % to 1 wt %, and Al: the remainder, and

wherein the forming of the second Al alloy foam comprises rolling the first Al alloy foam while the first Al alloy foam is being heated in a range of 530° C. to 630° C.

12. The method of claim 9 , wherein the forming of the second Al alloy foam comprises rolling the first Al alloy foam to a reduction ratio of 5% to 25%.

13. A method of manufacturing aluminum (Al) alloy foam, the method comprising:

adding magnesium (Mg) to molten aluminum (Al) to form a molten Al alloy; and

adding hollow ceramic spheres to the molten Al alloy by forming a vortex in the molten Al alloy by using a stirrer.

14. The method of claim 13 , wherein the forming of the vortex comprises stirring the molten Al alloy by rotating the stirrer at a rotation speed ranging from 500 rpm to 1,200 rpm.

15. The method of claim 14 , wherein the stirring of the molten Al alloy comprises stirring the molten Al alloy at a temperature ranging from 750° C. to 850° C.

16. The method of claim 13 , further comprising preheating the hollow ceramic spheres to a temperature ranging from 100° C. to 180° C., before the adding of the hollow ceramic spheres.

17. The method of claim 13 , wherein a content of Mg is 2.0 wt % to 8.0 wt %.

18. The method of claim 13 , wherein the hollow ceramic spheres have a particle size ranging from 125 μm to 500 μm, and

wherein a content of the hollow ceramic spheres is 20 Vol. % to 50 Vol. %.