Developing hydrogentolerant microstructures for an α2 titanium aluminide alloy

The feasibility of developing hydrogen-tolerant microstructures for α₂ titanium aluminide alloys by heat treatment has been investigated. In particular, a variety of microstructures for the Ti-24Al-11Nb (in atomic percent) alloy was developed by manipulating the heat-treatment conditions. After screening by the Vicker hardness tests, three microstructures were evaluated for their resistance to hydrogen embrittlement by performing sustained load creep tests in a gaseous hydrogen environment at an elevated temperature, followed by post-creep, slow-rate tensile tests at room temperature. Tensile tests of hydrogen-exposed specimens without prior creep exposure were also performed. The results indicate that one particular microcstructure of the Ti-24Al-11Nb alloy is resistant to hydrogen embrittlement under the test conditions and hydrogen contents investigated, providing evidence that heat-treatment techniques can be used to develop hydrogentolerant microstructures for α₂ titanium aluminide alloys.