· Aleaciones ligeras ·
Y Wang, G Liu and Z Fan
Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University, UK
67th World Foundry Congress
Mechanical properties and microstructural evolution of rheo-diecast (RDC)
AZ91D alloy during heat treatment (HT) have been studied. The semi-solid
processed alloy exhibits a unique solidification microstructure featuring the
uniformly distributed primary a-Mg globules, the fine secondary a-Mg
grains and the b-Mg17Al12 network. Compared with high-pressure die-cast
AZ91D alloy, the RDC alloy displays a faster solution response and
accelerated precipitation during HT. A new HT schedule Tx, has been
developed, which was carried out at a temperature close to the solvus to
break up the b-phase network. HT offers improvement to mechanical
properties and the Tx treatment gives a superior combination of strength
and ductility. The accelerated HT kinetics for the RDC alloy and the lower
temperature and shorter time of the Tx indicate a considerable reduction in
HT cost.
