“ZnAl36Cu3” Non-standard alloy
The dendritic cast structure is characterised by strong segregations during solidification: From the inside (light) to the outside, the zinc content in the dendrites increases from approx. 33% by mass to approx. 83%. The pearlite-like lamellar Al-Zn structure at the outer dendrite edge is formed by a eutectoid transformation. The intermetallic precipitates in the interdendritic space are a Zn-rich Zn-Cu-Al phase (bright in the light microscope and in the BSE) and an Al-rich phase of approximate composition Al4Cu3Zn (dark).
The hardness is 103 HV0.5.