Characterization, processing, and alloy design of NiAl-based shape memory alloys

Journal Article · Fri Apr 01 04:00:00 EST 1994 · Materials Characterization; (United States)

DOI:https://doi.org/10.1016/1044-5803(94)90084-1· OSTI ID:7199346

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

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

The microstructures and phase transformations in binary Ni-Al, ternary Ni-Al-Fe, and quaternary Ni-Al-Fe-Mn shape memory alloys (SMAs) were investigated by light and electron microscopy, electron and X-ray diffraction, and differential scanning calorimetry. The effects of alloying additions (B, Fe, and Mn) on martensite stability, shape recovery, and tensile ductility were also studied. NiAl-based SMAs can be made ductile by alloying with B for enhanced grain boundary cohesion and Fe for improved bulk properties. Iron has the undesirable effect that it decreases the martensite to austenite transformation temperatures (A[sub p]). Fortunately, A[sub p] can be increased by decreasing the equivalent Al content of the alloy. In this way, a high A[sub p] temperature of [approximately]190 C has been obtained without sacrificing ductility. Recoverable strains of [approximately]0.7% have been obtained in a Ni-Al-Fe alloy with A[sub p] temperature of [approximately]140 C. Manganese additions (2--10%) lower A[sub p], degrade hot workability, and decrease room temperature ductility. Good-quality, ductile SMA ribbons have been produced by melt spinning. However, additional alloy design is required to suppress the aging-induced embrittlement caused by Ni[sub 5]Al[sub 3] formation.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7199346
• Journal Information: Materials Characterization; (United States), Journal Name: Materials Characterization; (United States) Vol. 32:3; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360100* -- Metals & Alloys
ALLOYS
ALUMINIUM ALLOYS
BORON
ELEMENTS
FABRICATION
IRON
IRON ALLOYS
MANGANESE
MANGANESE ALLOYS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
METALS
MICROSTRUCTURE
NICKEL ALLOYS
PHASE TRANSFORMATIONS
SEMIMETALS
TRANSITION ELEMENTS