Microstructure of a nickel insert, a special copper alloy, and a cast joint between them

This work deals with the characterisation of the microstructure of a nickel insert, a special copper alloy and the cast joint between them after their use as a glass manufacturing mould. The microstructure was characterised by optical microscopy, scanning electron microscopy and microanalysis by energy dispersive X-ray spectroscopy.

It was found that the nickel insert contained 7 at. % Si and 0.3 at. % Fe. The special copper alloy contains undesirable phases or compounds, including lead, aluminium-based oxides and borides. The borides are either iron-, iron-chromium- or chromium-based with different stoichiometries between metal components and boron. The cast joint between the nickel insert and the special copper alloy has evidence of mixing the two alloys, while only in some areas porosity and oxides prevented the formation of a suitable cast joint. Aluminium-based oxides and some borides could be the cause of the formation of cracks due to their morphology.