Microstructure and grain refining performance of equal-channel angular-pressed Al–5%Ti–1%B master alloy on pure aluminum

Abstract

Al–5%Ti–1%B master alloy was subjected to equal-channel angular pressing (ECAP) by route A at room temperature. The effect of the ECAP on the size and the distribution of Al3Ti and TiB2 particles, the fading resistance of the Al–5%Ti–1%B master alloy and the grain refining performance of pure Al ingots with the addition of the Al–5%Ti–1%B master alloy before and after ECAP have been investigated. The large platelet Al3Ti particles were fragmented into fine blocky Al3Ti particles from ~88 to ~25 μm after eight ECAP passes, and the TiB2 particles were well dispersed in the Al matrix. It has been revealed that grain refining efficiency was improved by adding the Al–5%Ti–1%B master alloy after ECAP to the Al melt. The mean grain size of α-Al was decreased from ~1220 to ~70 μm with increasing the number of ECAP passes. It has been proved that the grain size of α-Al could be well fitted by the length of Al3Ti particles and the growth restrict factor. Al–5%Ti–1%B master alloy after four ECAP passes appeared to have a better fading resistance due to fine blocky Al3Ti particles.