Aging effects in a Cu-12Al-5Ni-2Mn-1Ti shape memory alloy
- Dalian Univ. of Technology (China). Dept. of Materials Engineering
- City Univ. of Hong Kong, Kowloon (Hong Kong). Materials Science Center
The isothermal aging effects in an as-quenched Cu-11.88Al-5.06Ni-1.65Mn-0.96Ti (wt pct) shape memory alloy at temperatures in the range 250 C to 400 C were investigated. The changes in the state of atomic order and microstructural evolutions were traced by means of in situ X-ray diffraction and electrical resistivity measurements, as well as transmission electron microscopy (TEM) and optical observations. The kinetics of the aging process, i.e., the temperature and time dependence of the properties including hardness, resistivity, martensitic transformation temperatures, and shape memory capacity were characterized, and at least three temperature-dependent aging stages were distinguished: (1) D0{sub 3} or L2{sub 1} atomic reordering, which causes the martensic transformation temperatures to shift upward and leads the M18R martensite to tend to be a N18R type structure; (2) formation of solute-depleted bainite which results in a drastic depression in martensitic transformation temperatures and loss of the shape memory capacity, accompanied by the atomic disordering in both the remaining parent phase and bainite; and (3) precipitation of the equilibrium {alpha} and {gamma}{sub 2} phases and destruction of the shape memory capacity.
- Sponsoring Organization:
- National Natural Science Foundation of China, Beijing, BJ (China)
- OSTI ID:
- 484846
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 28, Issue 4; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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