Microstructure and mechanical properties of Ti-6Al-4V produced by electron beam melting of pre-alloyed powders

Purpose - The purpose of this paper is the microstructural and mechanical characterization of a biomedical Ti-6Al-AV alloy produced by electron beam melting, and the study of the stability of the as-built microstructure upon heat treatment. Design/methodology/approach - Ti-6Al-4V alloy produced by electron beam melting has been mechanically characterized through tensile and fatigue testing. Its microstructure has been investigated by optical observation after etching and by X-ray diffractometry analysis. The stability of the microstructure of the as-built material has been deepened carrying out suitable heat treatments, after an analysis by dilatometry test. Findings - The microstructure of a Ti-6Al-AV alloy produced by electron beam melting has a very fine and acicular morphology, because of the intrinsically high-solidification rate of the process. This microstructure is very stable, and the traditional thermal treatments cannot modify it; the microstructure changes significantly only when an amount of strain is introduced in the material. However, the mechanical properties of the alloy produced by electron beam melting are good. Originality/value - The paper provides evidence of the microstructural stability of the material produced by electron beam melting. Even if the microstructure of the as-built material is not recommended by the specific ISO standard, the related mechanical properties are fully satisfactory. This is a significant indication from the point of view of the production of Ti-6Al-4V orthopaeclic and dental prostheses by electron beam melting.