Influence of Solidification Microstructure on Hardness and Wear Resistance in Al-33Cu-3.2Bi Alloy

Abstract

Research with aluminum alloys containing Bi has been developed in recent decades due to the great potential that these alloys present for the manufacture of components subjected to friction conditions. In the literature there are many doubts to be clarified about the interrelationship between the microstructure, mechanical properties, and wear resistance of unsteady-state directionally solidified multicomponent Al-Cu alloys, with high Cu content and containing Bi. Thus, this work aimed to investigate the effect of eutectic spacings (λE) on the hardness and wear resistance in the Al-33Cu-3.2Bi (wt.%) alloy by means of a water-cooled device. Rockwell B hardness (HRB) and micro-abrasive wear tests using a fixed rotating sphere, were carried out on solidified samples in positions from the heat transfer interface. In the wear tests, two durations were evaluated: 7 minutes and 28 minutes. The wear parameters evaluated were worn volume (VD) and wear rate (TD). After the aforementioned tests, the HRB, VD and TD values were correlated with the measured λE values. The results showed that finer microstructures, that is, smaller λE, promoted higher HRB values. On the other hand, VD and TD decreased for coarser microstructures, i.e., presented high wear resistance for higher λE values.

Keywords

• Unsteady-state upward solidification process
• Eutectic microstructure
• Hardness
• Wear
• AlCuBi Alloys