Microstructures and hydrogen embrittlement of Ti-49 at% Al were investigate
d. Results showed that there were three kinds of microstructures formed by
heat treatment at 1423, 1573 and 1703 K. The specimens which were heat-trea
ted at 1573 K, showed better elongation than the others on tensile tests at
room temperature, and this kind of specimens were used to investigate the
effect of hydrogen on tensile properties of this alloy. After heat-treatmen
t in hydrogen gas at 1073 K for 3 h, the specimens were divided into three
groups. In the first group, they were tensile-tested at room temperature in
vacuum; in the second group, they were heat-treated at 823 K for 1.5 h in
argon gas followed by tensile-testing at room temperature in vaccum; and in
the third group, they were tensile-tested at 473 or 573 K in vacuum. Resul
ts showed that for the specimens precharged with hydrogen, the elongation w
as decreased significantly at room temperature, and that the decreased elon
gation was recovered by removing hydrogen at 823 K in Ar gas, although it w
as not recovered to that of the specimens without hydrogen. This means that
hydrogen decreases the room temperature elongation of this alloy. For the
precharged specimens the elongation was also decreased at 473 and 573 K in
vacuum. This may indicate that hydrides in the precharged specimens affect
the tensile properties in vacuum. (C) 2000 Elsevier Science Ltd. All rights
reserved.