Effect of starting powder properties on the structure and mechanical characteristics of Al-8Cr-1.5Fe alloy for high-temperature applications

A high-temperature Al-8Cr-1.5Fe alloy has been developed for applications in the range from room temperature to 300A degrees C. The billets are obtained in two ways: using gas-atomized and water-atomized powders. Structural analysis shows that particles of the second phase in the water-atomized powders are finer and their number in the aluminum matrix is greater than that in the gas-atomized powders. The rods extruded from the water-atomized powders have much higher hardness, ultimate strength, and yield stress than those from the gas-atomized powders, plasticity being acceptable at all temperatures (20, 190, and 300A degrees C). An additional powder metallurgy operation-pulsed hot pressing-does not increase the strength of billets from either the water-atomized or gas-atomized powders. The alloy based on the water-atomized 0-63 mu m powder shows the maximum strength: 483, 332, and 261 MPa at 20, 190, and 300A degrees C, respectively.