Effect of Rolling on the Microstructure and Properties of Cast Al-10Ce-4Mg Alloy.

Aluminum alloys based on the Al-Ce-Mg system, with microstructure and properties weakly sensitive to elevated temperatures, are developed for applications such as thermal engine blocks and supersonic aircraft fuselage components. Cast Al-10Ce-4Mg (wt%) was produced by slab casting and further processed by rolling. Rolling with an area reduction of 54% results in a 97% increase in strength (tensile strength of 269 MPa at room temperature) and a more than a factor of two increase in strain at failure relative to the as-cast (AC) state. We show that Al-10Ce-4Mg is highly stable upon exposure to elevated temperature: 83% strength retention after exposure to 300 °C for 100 h, without reduction in the strain at failure. The yield stress (YS) follows the same trend, increasing by ~40% upon rolling and retaining 92% of its value after exposure to 300 °C for 100 h. The ratio of the strength at 300 °C to the strength at room temperature is 0.45, which is larger than the respective ratio of most commercial Al alloys. Rolling increases the dislocation density and introduces texture, while not modifying the grain size significantly and fragmenting only the largest intermetallics. Exposure to elevated temperatures up to 100 h has no measurable effect on grain size and intermetallic distribution, while slightly changing texture. This microstructural evolution is used to rationalize the observed changes in mechanical properties.