Room-temperature magnetocaloric effect of Ni-Co-Mn-Al Heusler alloys

Abstract

Magnetocaloric effect of the Ni-Co-Mn-Al quaternary alloys was evaluated with the aim of fine-tuning the composition such that the temperature at which the maximum entropy change (vertical bar Delta S-M vertical bar(pk)) occurs coincided with room temperature. Out of the three alloys tested (Ni41.5Co8.5Mn32Al18, Ni41Co9Mn32.5Al17.5 and Ni41Co9Mn32Al18), Ni41Co9Mn32Al18 was optimal with vertical bar Delta S-M vertical bar(pk) of 2.1 J kg(-1) K-1 at 10 kOe observed at 300 K as designed and the refrigeration capacity (RC) was 52 J kg(-1). Both values do compare favorably with other Heusler-type alloys, considering the relatively low material cost of the Ni-Mn-Al alloy. In addition, Ni41.5Co8.5Mn32Al18 and Ni41Co9Mn32Al18 alloys were chemically joined (using an epoxy) to attain vertical bar Delta S-M vertical bar(pk) and RC values that nearly corresponded to the average values of the original alloys, providing a method for further tailoring the magnetic properties of the refrigerant in addition to the refinement of the composition. (C) 2014 Elsevier B.V. All rights reserved.This work was supported by the Human Resource Development Program (No. 20114010203020) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy