S. Rubini et al., NMR INVESTIGATION OF THE MARTENSITIC-TRANSFORMATION IN FINE PARTICLESOF NI-AL ALLOYS, Physical review. B, Condensed matter, 49(14), 1994, pp. 9331-9335
Al-27 NMR results are presented for three Ni-Al alloys with compositio
n 62%, 62.5%, and 63% Ni undergoing a thermoelastic martensitic phase
transformation below room temperature. By a method of analysis of the
NMR data recently developed by us [Phys. Rev. B 46, 10 563 (1992)], we
measure the growth of the volume fraction of martensite on cooling fo
r samples having different particle sizes (1 mm-50 mum). We observe an
incomplete transformation in the fine particle sample (less than 150
mum). The effect can be explained as due to the presence of austenite
trapped in intramartensitic regions near the center of the particles.