Influence of Cold-Sprayed Al/Ti Deposition on High-Temperature Oxidation and Mechanical Properties Deterioration of Ti-Al-Nb Intermetallic Substrates

Four powder blends of Al and Ti were cold sprayed on Ti-Al-Nb substrates at 300°C. Test samples were heat treated in Ar at 500 °C then exposed to 950 °C air for 100-500 h. It was found that oxidation rates were significantly reduced by the coatings, especially those with lower Ti content. However, four-point bending tests revealed that the deposition of the protective layer reduced the flexural strength of the coated substrate. The results indicate that oxidation is not the only factor influencing the mechanical properties of intermetallics at high temperatures.