Electron beam melting (EBM), as one of metal additive manufacturing technologies, is considered to be an innovative industrial production technology. Based on the layer-wise manufacturing technique, as-produced parts can be fabricated on a powder bed using the 3D computational design method. Because the melting process takes place in a vacuum environment, EBM technology can produce parts with higher densities compared to selective laser melting (SLM), particularly when titanium alloy is used. The ability to produce higher quality parts using EBM technology is making EBM more competitive. After briefly introducing the EBM process and the processing factors involved, this paper reviews recent progress in the processing, microstructure, and properties of titanium alloys and their composites manufactured by EBM. The paper describes significant positive progress in EBM of all types of titanium in terms of solid bulk and porous structures including Ti-6Al-4V and Ti-24Nb-4Zr-8Sn, with a focus on manufacturing using EBM and the resultant unique microstructure and service properties (mechanical properties, fatigue behaviors, and corrosion resistance properties) of EBM-produced titanium alloys.
An investigation on the formation of ␣ Љ martensite and its influence on Young's modulus and mechanical properties of forged Ti-29Nb-13Ta-4.6Zr (wt pct) alloy is reported in this article. For icewater-quenched specimens after solution treatment at 1023, 1123, and 1223 K in the single  -phase field for 1.8, 3.6, 14.4, and 28.8 ks, X-ray diffraction and internal friction measurements showed that the volume fraction of the ␣ Љ martensite changes with both solution temperature and time. This effect has been attributed mainly to the influence of grain size of the  -parent phase on the stability of the  phase and, consequently, on the martensitic start (M S ) temperature. A critical grain size of 40 m was identified for the  phase, below which the martensitic transformation is largely suppressed because of low M S temperature. With the  grain size increasing above this critical value, the volume fraction of the ␣ Љ martensite increases significantly at first and then decreases gradually with further grain growth. The ␣ Љ martensite was shown to possess good ductility and, compared to the  phase, lower strength and hardness but nearly identical Young's modulus in the studied alloy.
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