A yttrium-containing high-temperature titanium alloy additively manufactured by selective electron beam melting

Abstract

A yttrium-containing high-temperature titanium alloy (Ti-6Al-2.7Sn-4Zr-0.4Mo-0.45Si-0.1Y, mass fraction, %) has been additively manufactured using selective electron beam melting (SEBM). The resulting microstructure and textures were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron backscattered diffraction (EBSD) and compared with the conventionally manufactured form. A notable distinct difference of microstructures is that additive manufacturing by SEBM enables homogeneous precipitation of fine Y₂O₃ dispersoids in the size range of 50-250 nm throughout the as-fabricated alloy, despite the presence of just trace levels of oxygen (7×10^-4, mass fraction) and yttrium (10^-3, mass fraction) in the alloy. In contrast, the conventionally manufactured alloy shows inhomogeneously distributed coarse Y₂O₃ precipitates, including cracked or debonded Y₂O₃ particles.

Keywords

titanium alloys / additive manufacturing / rare earth elements / yttrium / selective electron beam melting

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