Mechanical Behaviour of Ausformed and Marformed Ti-Rich Ni-Ti Shape Memory Alloys
Shape memory effect (SME) in Nickel-Titanium (Ni-Ti) alloys is ascribed to the thermoelastic reversible martensite phase transformation. Phase transformation is established to be affected by the pre- thermal and mechanical history of the alloy. The present work deals with the effect of mechanical working, known as ‘marforming’ and ‘ausforming’, on the phase transformation characteristics and mechanical behaviour of Ti-rich Ni-Ti alloy. Tensile study and measurement of the hardness data were carried out at room temperature. Mere heat treatment or heat treatment at 773 K after the marforming shows similar characteristics, whereas, the as-received and the ausformed samples exhibit different behaviours. Hardness numbers of the heat treated samples are found to be smaller than those of the as-received and mechanically worked samples.
António Torres Marques, António Fernando Silva, António Paulo Monteiro Baptista, Carlos Sá, Fernando Jorge Lino Alves, Luís Filipe Malheiros and Manuel Vieira
A. S. Paula et al., "Mechanical Behaviour of Ausformed and Marformed Ti-Rich Ni-Ti Shape Memory Alloys", Materials Science Forum, Vols. 587-588, pp. 635-639, 2008