INVESTIGADORES
MALARRIA Jorge Alberto
congresos y reuniones científicas
Título:
Load-biased martensitic transformation strain of Ni-Ti-Co strip obtained by Twin-Roll Casting technique
Autor/es:
L. ISOLA, P. LA ROCA, A. ROATTA, PH. VERMAUT, P. OCHIN, J. MALARRÍA
Lugar:
Paris
Reunión:
Simposio; Colloque Plasticité 2013; 2013
Institución organizadora:
Société Française de Métallurgie et de Matériaux
Resumen:
The twin-roll casting (TRC) is a powerful
technique, which allows us to obtain semi-finished strips in one-step
procedure. Moreover, a favorable microstructure with a columnar grain
morphology and small grain size can be achieved. The NiTi alloys of
near-equiatomic composition are recognized as the most attractive shape memory
alloy for a wide variety of applications. A small amount of Co atoms are
introduced in order to promote the separation of the B2->R and R->B19'
transformations, due to a shift of Ms(B19´) downwards lower
temperatures range.
The aim of this work is to
analyze the mechanical proprieties of the Ti-47Ni-3Co (at.%) strips, in
particular the maximum recoverable shape memory strain. The microstructure was
characterized by optical and electronic microscopy, while the texture was
measured using X-ray diffraction. The experiments show the strong texture of
the columnar grain structure, were the austenite grains are oriented with the
{001}B2//ND, and their average diameter size is of around 3 μm. On the
basis of the measured texture, the
maximum B2->B19' transformation strain was estimated at 5,6 %, using
a Sachs-type upper bound model which averages the most favorable martensite variants in each
grain, disregarding interactions between
them. This value is in good
agreement with the maximum recoverable strain measured in thermal cycles under
constant stress experiments.