Titanium aluminides for automotive applications processed by electron beam melting

Powders of alloys Ti-48Al-2Cr-2Nb (48-2-2) and Ti-48Al-2Nb-0.7Cr-0.3Si (RNT650) were used to fabricate test samples and turbocharger wheel prototypes, respectively, by electron beam melting. This additive manufacturing technology uses an electron beam to generate parts by selectively melting the powder in a layer-by-layer way based on CAD data. The parts of both alloys were fully densified with only minor percentages of build flaws. For alloy 48-2-2, a loss of Al of about 1.4 wt% is observed, while the levels of impurities are comparable between the powder and the part. Furthermore, the microstructure was investigated after EBM and after EBM + heat treatment for alloy 48-2-2. It is characterized by equiaxed grains after EBM. An additional heat treatment transformed this microstructure into a fully lamellar one showing that the microstructure was homogenized.