Deformation mechanisms in rapidly solidified aluminum alloys

The deformation mechanisms of four rapidly solidified (RS) and hot extruded aluminum alloys were investigated. Al-8.8Fe-3.7Ce (all composition in wt percent) and Al-8.9Fe-6.9Ce alloys produced from RS powders and two Al-8Fe-2Mo alloys one produced from RS ribbons and the other from powders, respectively, were creep tested in the temperature range 250 to 350 C over a range of stresses from 15 to 250 MPa. The Al-8.8Fe-3.7Ce alloy exhibited a diffusional creep region at low stresses and a power law creep region as the stress increased beyond a given transition stress. To investigate the influence of the thermal degradation on the creep behavior of the Al-Fe-Ce alloys, both alloys were heat treated for 165 hours at 450, 500 and 550 C, respectively, and creep tested at 300 C. Both a diffusional and a power law region was observed for both alloys and all heat treatment temperatures. An increase in the diffusional creep rates was observed for the heat treated alloys instead of the expected decrease, confirming that the grain size of the material does not determine the creep rates in the diffusional creep region