Abstract: The effects of bor on content and tran sverse specimens on the stress-rupture property athigh temper atures of dir ectionally solidified (DS) Ni3Al alloy have been investigated. The addition of bor on induces grain boundary strengthening and the change of dislocation configur ation, which improves the stress-r upture life at high temperatures of DS Ni3Al. On the other hand, the addition of boron fines the structure and increases the number of gr ain-boundaries. The instability of the stress-rupture property at high temperatures of DS NI 3Al tra nsverse specimens is dependent on the sampling position.

Key words: bor on, content, sampling, stress rupture strength, effects