Thermal stability of aluminum–cerium binary alloys containing the Al–Al11Ce3 eutectic

Abstract

Abstract The capability of Al–Ce binary alloys, containing from 5 to 20 wt% Ce and ranging from hypo-to hypereutectic compositions, to retain strength at high temperatures was assessed through the uniaxial compression up to 500 °C. As a reference the A380 (Al–8Si–3Cu, wt%) commercial alloy and pure Al were examined under identical conditions. The Al–Ce cast alloys, strengthened by the Al11Ce3 eutectic and proeutectic phases, reached at room temperature the yield stress of 60–100 MPa, being higher than 40 MPa measured for pure Al but well below 170 MPa achieved for A380. During high temperature compression, the yield stress of Al–Ce alloys reduced at a steady rate with temperature, retaining at 400 °C and 500 °C only 50% and 25%, respectively, of its initial room temperature level. This is in contrast to 80–90% of the initial hardness retained after 168 h heating at 500 °C. Although the high initial yield stress of the A380 alloy reduced sharply in the temperature range of 200–400 °C, its retained value after both the short and long term heat exposures was still above the level measured for Al–Ce alloys. It is concluded that the Al11Ce3 eutectic and proeutectic phases have a limited effectiveness in room temperature strengthening of Al–Ce binary alloys and in retaining their strength at increased temperatures. The high hardness retention ratio of Al–Ce alloys, accompanied by the low coarsening rate of the Al11Ce3 phase, do not correlate with the observed high yield stress reduction with testing temperatures.