Mechanical behavior and phase stability of NiAl-based shape memory alloys

Technical Report · Fri Dec 31 04:00:00 EST 1993

DOI:https://doi.org/10.2172/10154030· OSTI ID:10154030

George, E P; Liu, C T; Horton, J A ^[1]; Kunsmann, H; King, T ^[2]; Kao, M ^[3]

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1. Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.
2. Eaton Corp., Milwaukee, WI (United States)
3. Johnson Controls Inc., Milwaukee, WI (United States)

NiAl-based shape memory alloys (SMAs) can be made ductile by alloying with 100--300 wppm B and 14--20 at.% Fe. The addition of Fe has the undesirable effect that it lowers the temperature (A{sub p}) of the martensite {yields} austenite phase transformation. Fortunately, however, A can be raised by lowering the ``equivalent`` amount of Al in the alloy. In this way a high A{sub p} temperature of {approximately}190 C has been obtained without sacrificing ductility. Furthermore, a recoverable strain of 0.7% has been obtained in a Ni-Al-Fe alloy with A{sub p} temperature of {approximately}140 C. Iron additions do not suppress the aging-induced embrittlement that occurs in NiAl alloys at 300--500 C as a result of Ni{sub 5}Al{sub 3} precipitation. Manganese additions (up to 10 at.%) have the effect of lowering A{sub p}, degrading hot workability, and decreasing room-temperature ductility.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10154030
• Report Number(s): CONF-9308122--18; ON: DE94012336
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102
360103
ALUMINIUM ALLOYS
BORON
BORON ADDITIONS
CALORIMETRY
CRYSTAL-PHASE TRANSFORMATIONS
EXPERIMENTAL DATA
INTERMETALLIC COMPOUNDS
IRON
IRON ALLOYS
MANGANESE
MANGANESE ALLOYS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
MICROSTRUCTURE
NICKEL BASE ALLOYS
PHASE STUDIES
SHAPE MEMORY EFFECT
STRUCTURE AND PHASE STUDIES
TRANSITION TEMPERATURE
X-RAY DIFFRACTION