Intermartensitic Transformations in Ni2Mn1−xCoxGa Heusler Alloys

Authors

Mahmud Khan, Southern Illinois University Carbondale
Shane Stadler, Southern Illinois University Carbondale
Naushad Ali, Southern Illinois University Carbondale

Comments

© 2006 American Institute of Physics

Published in Journal of Applied Physics, Vol. 99 No. 8 (2006) at doi: 10.1063/1.2176054

Abstract

Ni₂MnGa that possesses a Heusler L2₁ structure undergoes a martensitic transformation from the parent cubic (austenitic) phase to a low temperature complex tetragonal structure at T_M = 202 K and has a Curie temperature of T_C = 376 K. Some research groups have observed an intermartensitic transformation at a temperature T_I<T_M, in Ni₂MnGa single crystals. In this work detailed studies on the influence of substitution in the Mn subsystem by magnetic Co on the intermartensitic transformation properties of Ni₂Mn_1−xCo_xGa compounds have been done by magnetization (5–400 K) and thermal expansion (80–300 K) measurements. The samples Ni₂Mn_0.92Co_.08Ga, Ni₂Mn_0.91Co_.09Ga, and Ni₂Mn_0.90Co_.10Ga were studied. The intermartensitic transformation is observed in all of these alloys. As the Co concentration increases, the transformation becomes more pronounced and the temperature range for which the alloys stay in the intermartensitic state decreases as Co concentration increases. Similarities were observed between the magnetization and thermal expansion curves. The results are discussed in terms of the internal stress produced as a result of the Co substitution.

Recommended Citation

Khan, Mahmud, Stadler, Shane and Ali, Naushad. "Intermartensitic Transformations in Ni2Mn1−xCoxGa Heusler Alloys." (Apr 2006).