Designing a Microstructural Array Associated with Hardness of Dual-phase Cu-Zn Alloy Using Investment Casting

A comparative investigation on the microstructural morphologies and hardness values of Cu-35 wt.% Zn and Cu-30 wt.% Zn with 1.5 wt.% Al content is provided. Distinctive specimens by using traditional investment casting were produced. Specimens withdrawn from distinct locations along the castings were thermally and microstructural analyzed. Thermally and chemically induced microstructural modifications affecting the microstructure and hardness are discussed. It is found that components (specimens) located at different positions along of the pattern tree casting have distinctive hardness values. This is associated with Cu segregation and cooling rate. It is also found that solidified piece under a cooling rate ~0.12 K/s has hardness 20% higher than the specimen solidified under 0.07 K/s. Duplex brass with Widmanstätten structure constitutes the resulting microstructure array. This seems to be associated with Al content, while both Zn and Al contents are associated with cooling rate as responsible parameter to induce Widmanstätten structure formation.