Analysis of Thermal and Structural Parameters and Microhardess Variations in Different Al-Cu Alloys Directionally Solidified

Abstract

The columnar — to — equiaxed transition (CET) was investigated in Al-Cu alloys (Al-lwt%Cu, Al-4.5wt%Cu, Al-15wt%Cu and Al-33.2wt%Cu) solidified directionally from a chill face in a vertical setup. The CET occurs when the temperature gradient in the melt ahead of the columnar front reach critical values. Also, we investigate correlations between structural parameters (grain size) with Vickers microhardness measurements in the directionally solidified samples. We observed that the Vickers microhardness is greater in the equiaxed zone than in the columnar or columnar to equiaxed transition (CET) zone, additionally, is greater on the edges of the samples than in the centre. Also, we determined that the grain size increases from the columnar to equiaxed structure.