Kinetic arrest of direct and reverse martensitic transformation and exchange bias effect in Mn49.5Ni40.4In10.1 melt spun ribbons

"Phase coexistence phenomena related to direct and reverse martensitic transformation have been studied in melt spun ribbons of the magnetic shape memory alloy Mn49.5Ni40.4In10.1. For magnetic fields above 10 kOe martensitic transformation undergoes a progressive kinetic arrest. The metastable character of the field-cooled frozen fraction of austenite into martensite was verified. An atypical incomplete reverse martensitic transformation of thermal origin was also observed. The zero-field cooled thermomagnetization curve measured at 50 kOe shows a decrease below 30 K that was accompanied by the occurrence of exchange bias effect suggesting the strengthening of antiferromagnetic interactions in martensite in such temperature range.