Synthesis of Al-SrB6 composite via powder metallurgy processing

The potential of powder metallurgy processing for the manufacture of Al-SrB6 composites was explored. Al4Sr particles fractured extensively during the ball milling of Al-15Sr/Al-4B powder mixtures. There was no interaction between the Al4Sr and AlB2 compounds across the section of the aluminium grains in the as-milled state. SrB6 formed, when the ball milled powder blends were subsequently annealed at sufficiently high temperatures. Ball milling for 1 h was sufficient for SrB6 to become the major constituent in powder blends annealed at 700 degrees C while it took 2 h of ball milling for powder blends annealed at 600 degrees C. Higher annealing temperatures and longer ball milling time encouraged the formation of the SrB6 compound while the latter made a great impact on the microstructural features of the Al-SrB6 composite. The SrB6 compound particles were much smaller and more uniformly distributed across the aluminium matrix grains in powder grains ball milled for 2 h before the annealing treatments at 600 degrees C and 700 degrees C

Effect of solution heat treatment on the age hardening capacity of dendritic and globular AlSi7Mg0.6 alloys

Abstract The effect of solution heat treatment on the age hardening capacity of dendritic and globular AlSi7Mg0.6 alloys was investigated in the present work to find out if solution treatment times are in fact shorter for rheocast parts. The morphology of the α-Al matrix, whether dendritic or globular, has no effect on the response of the alloy to T6 treatment. A solution treatment at 540 °C for 2 h suffices to fully solutionize the Mg and Si and the age hardening capacity of the AlSi7Mg0.6 alloy is impaired when it is 1 h or shorter. This is true for both dendritic and globular alloys. The expected favourable impact of the globular structure on the solution treatment times is believed to be offset by the relatively coarser structure in the globular alloy with respect to its dendritic counterpart.</jats:p