Characteristics of hydriding and hydrogen embrittlement of the Ti-Al-Zr alloy

The characteristics of hydriding and hydrogen embrittlement of the Ti-Al-Zr alloy were evaluated. The amount of hydrogen absorbed into the alloy at 500 degreesC was continuously monitored using a hydrogen pressure measurement. The rate of decrease in hydrogen pressure indicated a high absorption rate of hydrogen into the alloy, following a linear rate law. X-ray diffraction studies showed the formation of delta-phase titanium hydride (TiH1.97) after hydriding. At room temperature, the alloy showed much sensitivity to embrittlement in ductility by hydrogen. The delta-hydrides in the grain boundaries promoted the crack propagation in the presence of stress, leading to the cleavage failure mode. However, the tensile strengths were almost independent of the hydrogen content up to 1174 ppm. It is thus concluded that the delta-hydride acts to decrease the ductility without affecting tensile strengths. (C) 2002 Elsevier Science Ltd. All rights reserved.