Effects of Annealing on the Martensitic Transformation of Ni-Based Ferromagnetic Shape Memory Heusler Alloys and Nanoparticles

Metals

Tina Fichtner¹  Changhai Wang¹  Aleksandr A. Levin¹  Guido Kreiner¹  Catalina Salazar Mejia¹  Simone Fabbrici²  Franca Albertini²  Claudia Felser¹ 

[1]Max-Planck-Institute for Chemical Physics of Solids (MPI CPFS), Noethnitzer Str. 40, DE-01187 Dresden, Germany

[2] E-Mails:

[3]Institute of Materials for Electronics and Magnetism, National Research Council (IMEM-CNR), Parco Area delle Scienze 37/A, I-43124 Parma, Italy

[4] E-Mails:

关键词: phase transitions;    magnetism;    X-ray and electron scattering;   

DOI  :  10.3390/met5020484

来源: mdpi

【 摘 要 】

We report on the effects of annealing on the martensitic phase transformation in the Ni-based Heusler system: Mn₅₀Ni₄₀Sn₁₀ and Mn₅₀Ni₄₁Sn₉ powder and Co₅₀Ni₂₁Ga₃₂ nanoparticles. For the powdered Mn₅₀Ni₄₀Sn₁₀ and Mn₅₀Ni₄₁Sn₉ alloys, structural and magnetic measurements reveal that post-annealing decreases the martensitic transformation temperatures and increases the transition hysteresis. This might be associated with a release of stress in the Mn₅₀Ni₄₀Sn₁₀ and Mn₅₀Ni₄₁Sn₉ alloys during the annealing process. However, in the case of Co₅₀Ni₂₁Ga₃₂ nanoparticles, a reverse phenomenon is observed. X-ray diffraction analysis results reveal that the as-prepared Co₅₀Ni₂₁Ga₃₂ nanoparticles do not show a martensitic phase at room temperature. Post-annealing followed by ice quenching, however, is found to trigger the formation of the martensitic phase. The presence of the martensitic transition is attributed to annealing-induced particle growth and the stress introduced during quenching.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland