Hydrogen-boron interaction and its effect on the ductility and fracture of Ni{sub 3}Al

Journal Article · Tue Jul 01 04:00:00 EDT 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(96)00383-7· OSTI ID:524538

Cohron, J W ^[1]; George, E P; Heatherly, L; Liu, C T ^[1]; Zee, R H ^[2]

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1. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
2. Auburn Univ., AL (United States). Materials Engineering Program

Ni{sub 3}Al alloys, of nominal composition Ni-24 at.% Al and three different B concentrations (50, 100 and 500 wppm), were tensile tested at room temperature in high-purity H: gas at pressures ranging from {approximately}6 {times} 10{sup {minus}8} to 7 {times} 10{sup 3}Pa. The highest elongations to fracture were obtained in ultrahigh vacuum: {approximately}36, 45 and 60% for the 50, 100 and 500 wppm B alloys, respectively, With increasing H{sub 2} pressure, the ductility of all three alloys dropped precipitously. Accompanying this drop in ductility was a change in the fracture mode from predominantly transgranular to predominantly intergranular. An intriguing result of the present study is that, at the higher H{sub 2} pressures employed, B-doped Ni{sub 3}Al(50 or 100 wppm) is brittle and fractures predominantly integranularly, whereas B-free Ni{sub 3}Al is ductile and fractures predominantly transgranularly. This result indicates that B--by possibly promoting the dissociation of molecular H{sub 2} into atomic H--embrittles Ni{sub 3}Al in a dry H{sub 2} environment, unlike in H{sub 2}O-containing environments, where B suppresses grain boundary fracture and improves the ductility of Ni{sub 3} Al.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 524538
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 7 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
BORON ADDITIONS
DUCTILITY
ELONGATION
GRAIN BOUNDARIES
HYDROGEN EMBRITTLEMENT
INTERMETALLIC COMPOUNDS
METALLURGICAL EFFECTS
NICKEL ALLOYS
PRESSURE DEPENDENCE