Effect of equal channel angular pressing on microstructure and grain refining performance of Al–5%Ti master alloy

Abstract

The Al–5%Ti master alloy has been subjected to the equal channel angular pressing (ECAP) by route A at room temperature, and the grain refining performance of Al–5%Ti master alloy before and after ECAP with the use of an industrial purity Al has been evaluated. The effects of the ECAP on the size and the distribution of the TiAl3 particles, grain size, microhardness and electrical conductivity of pure Al ingots with and without adding the Al–5%Ti master alloy have been investigated. The large platelet-like TiAl3 particles were fragmented into the fine blocky TiAl3 particles from ∼270μm to ∼13μm uniformly distributed in the Al matrix after three ECAP passes. It has been revealed that microhardness of pure Al cast samples have been increased by adding the Al–5%Ti master alloy processed by ECAP; however, the electrical conductivity has deteriorated. The Al–5%Ti refiner processed by ECAP appeared to have an enhancing grain refining effect in comparison with that before ECAP. It has been proved that the grain size of α-Al could be well fitted by the length of TiAl3 particles and the growth restriction factor. The conclusion has been made that it is practical to enhance the grain refining effectiveness of the Al–5%Ti master alloy through the ECAP process by no more than three passes.