Intrinsic ductility and environmental embrittlement of binary Ni3Al

摘要: Polycrystalline, B-free Ni[sub 3]Al (23.4 at.% Al), produced by cold working and recrystallizing a single crystal, exhibits room temperature tensile ductilities of 3-5% in air 13-16% oxygen. These are considerably higher than anything previously reported, demonstrate that the intrinsic' ductility is much thought. They also show moisture present ordinary ambient can severely embrittle (ductility decreasing from high 16% oxygen to low 3% air). Fracture predominantly intergranular both This indicates that, while further GBs 3]Al, they persist as weak links even absence environmental embrittlement. However, not intrinsically brittle' once thought, since withstand relatively large plastic deformations prior fracture. Because B essentially eliminates embrittlement - major cause poor it concluded significant portion so-called effect must be related suppression moisture-induced B-doped fractures transgranularly, whereas intergranularly,more » have added strengthens GBs. A comparison with earlier work on Zr-doped shows Zr improves (and more dramatically) While exact mechanism this improvement clear at present, appears an (enhancing) GB strength (suppressing) embrittlement.« less