Environmental effects in NiTi-based alloys

Journal Article · Fri Jun 04 04:00:00 EDT 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00125-6· OSTI ID:684350

Zhu, J H; Liu, C T ^[1]

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1. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

Environmental embrittlement has been identified as one of the major causes for low ductility and poor fracture toughness in a number of ordered intermetallics containing reactive element,s such as Al, Ti, Si, Mn, V or Mo, when tested in moisture-containing environments at room temperature. This is believed to be a hydrogen embrittlement process which involves the reaction of reactive elements in intermetallic alloys with water vapor in air, and subsequent generation of atomic hydrogen that is transported into the interior of the specimen, leading to brittle crack propagation and fracture along grain boundaries and/or cleavage planes. In this communication, the authors report the tensile properties in different environments of two NiTi-based alloys with ordered B19 and B2 structures. The alloys were tested under controlled environments to observe the effects of moisture and hydrogen gas on the ductility of the alloys. The fracture surface observation shows that, consistent with the tensile test properties, the fracture mode doe snot change when tested in different environments. All the alloys showed ductile fracture, consistent with the good ductility of the materials.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 684350
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 1 Vol. 41; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DIFFUSION
HYDROGEN
HYDROGEN EMBRITTLEMENT
IRON ALLOYS
MOISTURE
NICKEL ALLOYS
TITANIUM ALLOYS