Wear behavior of Al-Sn-Cu alloys for sliding bearings modified with Bi

• Grant number: 24/08970-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2024
• End date: July 31, 2025
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: José Eduardo Spinelli
• Grantee: Vinicius Leme Andrade
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Al-Sn based alloys are classified as self-lubricating alloys with excellent potential for applications such as bearing bushes. The development of new alloys is ongoing research and involves modifying the base alloy with alloying elements. The goal is to increase both mechanical strength and wear resistance, or at least enhance one without reducing the other. Cu is a commonly used mechanical strengthening element in the Al-Sn system, and Bi has the potential to alter the morphology of the Sn phase. Bi, being relatively soft and immiscible in Al, can positively affect wear behavior by modifying and controlling the microstructure. While there is a reasonable understanding of role of the Cu in microstructure and wear, the impact of Bi is still poorly understood, whether in solidification, microstructure coarsening, mechanical properties, or wear. Thus, it is proposed to investigate an alloy with a composition close to industrial (Al-20%Sn-1%Cu, wt.%), and another (based on the first) with the addition of Bi: Al-20%Sn-1%Cu-2%Bi. The two ingots will be produced by transient directional solidification, allowing the study of samples with different microstructural scales (or coarsening), which will be investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, tensile tests, and wear tests. Using Thermo-Calc software, the influence of Bi on the solidification path of the alloy will be analyzed. Aspects of the microstructures such as fraction, morphology, size, and phase composition will be determined and correlated with the cooling rate associated with each sample during solidification of each alloy. Finally, the role of Bi in the tensile mechanical properties and wear behavior will be elucidated.