Effect of cooling rate on the microstructure and solidification parameters of Mg–3Al–3Nd alloy

The effect of cooling rate on the microstructure and solidification parameters of Mg–3Al–3Nd alloy was investigated by thermal analysis. The different cooling rates were chosen in the present work, which were attained by a stepped sand mold, ranging from 0.3 to 3.5 °C s−1. The solidification parameters were determined from the cooling curve as well as its first and second derivative curves. The results show that the microstructure and solidification parameters of Mg–3Al–3Nd alloy are influenced by changing the cooling rate. The nucleation temperature, undercooling temperature, the range of solidification temperature all increase with increasing the cooling rate. The precipitated temperature of Al2Nd and Al11Nd3 phases, recalescence undercooling temperature and total solidification time all decrease with increasing the cooling rate. The grain size of Mg–3Al–3Nd alloy is refined, and the intermetallic phases are distributed more uniformly with increasing the cooling rate. Furthermore, the volume fraction of intermetallic phases and the number density of Al2Nd particle also increase with increasing the cooling rate.