Abrasive and Oxidative Wear Mechanisms on Additively Manufactured Ti-6Al Alloy Against Al2O3: Effect of Microstructures and Hardness

Abstract

The increasing adoption of additive manufacturing (AM) in biomedical applications demands a deeper understanding of the wear behavior of AM Ti-6Al-4V alloy. The microstructures obtained from AM processes often require further tailoring through heat treatments to meet application demands. In this regard, this study investigates the dry sliding wear behavior of Ti-6Al-4V alloy produced by laser and electron beam powder bed fusion. Various microstructures were obtained through different heat treatments performed below and above the alloy (3 transus temperature. The microstructures were characterized by optical microscopy, scanning electron microscopy, and Vickers hardness testing. Wear tests were conducted under reciprocating sliding using an Al2O3 counter-body with different normal loads (1-5 N), and specific wear rates and coefficients of friction were analyzed. Results revealed different hardness values between 356.6 + 8.5 and 284.1 + 11.0 HV, associated with different microstructures, varying from a fully martensitic alpha ' structure to lamellar alpha+(3 structures with increasing heat treatment temperature. The wear mechanisms were a combination of abrasive and oxidative, with oxide debris contributing to tribolayer formation. Higher normal loads favored tribolayer formation, reducing the coefficient of friction from 0.664 + 0.021 to 0.544 + 0.004 and from 0.680 + 0.017 to 0.581 + 0.015 for the highest and lowest hardness conditions, respectively, and specific wear rate. The findings highlight that both hardness and tribolayer formation govern wear resistance, necessitating further studies on load effects in AM Ti6Al-4V alloys.Sao Paulo Research Foundation (FAPESP) [2020/05612-8, 2021/06516-51]; Ministerio de Ciencia e Innovacion (MICINN) [PID2020-112878RB-100/AEI/10.13039/501100011033]This work was supported by the Sao Paulo Research Foundation (FAPESP) [grant numbers #2020/05612-8 and #2021/06516-51; the CTI's Open Labs-Multiple Users and Shared Facilities from LAprint, CTI Renato Archer, research institution from MCTI; and partially funded by Ministerio de Ciencia e Innovacion (MICINN) , PID2020-112878RB-100/AEI/10.13039/501100011033 Development of Antimicrobial metallic surfaces. G. A. Longhitano would like to thank the Postdoctoral Researcher Program (PPPD) at FEM/UNICAMP