Microscopic analysis of the segregation in direct laser fabrication (DLF) of alloys

Abstract

Samples of Ti-25V-15Cr-2Al-0.2C, Ti-6V-4Al and Al-80Si (wt.%) have been prepared from the atomised powders using a selected range of processing conditions during direct laser fabrication in order to investigate the significance of segregation, which may be induced during melting and subsequent solidification. Energy dispersive X-ray analysis has been used to assess the segregation in these samples using a scanning electron microscope. It has been shown that for the wide range of processing conditions used, segregation is significant only in the Al-80Si alloy for a given range of process conditions. The results have been interpreted in terms of the liquidus-solidus characteristics of the alloys and of the influence of the different processing conditions used on the expected solidification behaviour.Samples of Ti-25V-15Cr-2Al-0.2C, Ti-6V-4Al and Al-80Si (wt.%) have been prepared from the atomised powders using a selected range of processing conditions during direct laser fabrication in order to investigate the significance of segregation, which may be induced during melting and subsequent solidification. Energy dispersive X-ray analysis has been used to assess the segregation in these samples using a scanning electron microscope. It has been shown that for the wide range of processing conditions used, segregation is significant only in the Al-80Si alloy for a given range of process conditions. The results have been interpreted in terms of the liquidus-solidus characteristics of the alloys and of the influence of the different processing conditions used on the expected solidification behaviour.