Superior tensile properties in additively manufactured Ti alloys

ABSTRACT

Thanks to rapid cooling rates and small melt pool sizes, selective laser melting (SLM) can be used to create novel microstructures difficult or impossible to achieve otherwise. This article overviews two types of SLM-fabricated Ti alloys exhibiting excellent strength and ductility. First, fully martensitic Ti-6Al-4 V alloys are produced with high yield strengths of >1100 MPa and total elongations of ~12–14%, comparable to those in fine α/β lamellar Ti-6Al-4 V. Second, hybridisation of different microstructures from existing alloys to generate a ‘composite of microstructures’ is introduced as a new strategy for producing heterogenous alloys with significantly enhanced performances. In particular, Ti alloys hybridised from different classes of Ti (α, α-β and β) have exhibited an excellent combination of high strength, work hardening ability and ductility, superior to conventional pure Ti andTi alloys.

KEYWORDS:

• Selective laser melting
• tensile properties
• heterogeneous microstructures
• martensitic Ti

Data availability

The data that support the findings of this study are available from the corresponding authors, A.Z and K.X., upon reasonable request.

Additional information

Notes on contributors

A. Zafari

Dr. Zafari

Dr. Ahmad Zafari received his PhD from the University of Melbourne in 2017, investigating phase transformation and grain refinement in severely deformed beta Ti alloys. He obtained M. S. from the University of Tehran in 2010, researching tribological behaviours of as-cast magnesium alloys at elevated temperatures, and B. S. from the Chamran University of Ahvaz in 2008, studying corrosion resistance of 316 stainless steel coated by polyelectrolyte nanofilms. Dr. Zafari has been a Research Fellow and the manager of the Metal 3D Printing Laboratory in the Department of Mechanical Engineering at the University of Melbourne since 2017. His research is currently focused on microstructures and mechanical properties in metallic materials, in particular titanium and iron alloys, produced by laser powder bed fusion.

Dr. Chandran

Dr. Prathap Chandran is currently a sessional lecturer at Victoria University. He is also a part time research assistant and tutor in the Department of Mechanical Engineering, the University of Melbourne. He received his PhD from the University of Melbourne in 2019, and prior to that received his M.Tech from Indian Institute and Technology, Madras, India, in 2011. Dr. Chandran’s research has been focused on microstructural evolution and mechanical properties of immiscible alloys and metal matrix composites processed by ball milling, HIP and plasma sintering.

Prof. Xia

Prof. Kenong Xia received his PhD from University of Southern California in 1988, after B.E. (1982) and M.E. (1984) from Northeastern University in China. He joined Comalco Research Centre as research scientist in 1988 before starting his academic career at the University of Melbourne in 1993. He is currently Professor of Materials in the Department of Mechanical Engineering at the University of Melbourne.