A recent study conducted by a research group has made significant progress in the field of magneto-superelasticity. This study focuses on a Ni34Co8Cu8Mn36Ga14 single crystal that achieved a remarkable 5% magneto-superelasticity by introducing ordered dislocations to form preferentially oriented martensitic variants during a magnetically induced reverse martensitic transformation. The findings of this research were published in the prestigious journal, Advanced Science.
Elasticity is a crucial property of materials, describing their ability to return to their original shape after deformation. In most metals, the typical strain for elasticity is around 0.2%. However, shape memory alloys and high entropy alloys can exhibit superelasticity with strains reaching several percent, often triggered by external stresses. Magneto-superelasticity, induced by a magnetic field, is particularly essential for contactless material operations and the development of new actuators and energy transducers with large stroke capabilities.
The research team, in collaboration with the High Magnetic Field Laboratory at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, conducted stress-constrained transition cycling (SCTC) training for the Ni34Co8Cu8Mn36Ga14 single crystal. By applying compressive stress, they introduced ordered dislocations with specific orientations that influenced the formation of martensitic variants during the reversible transformation triggered by a magnetic field. Phase field simulations confirmed the role of organized dislocations in shaping these preferred martensitic variants.
By combining reversible martensitic transformation with the preferential orientation of martensitic variants, the researchers were able to achieve a substantial 5% magneto-superelasticity in the single crystal. Furthermore, they designed a device utilizing a pulsed magnetic field with a pulse width of 10 ms, which demonstrated a significant stroke at room temperature due to the giant magneto-superelasticity. This device also showcased rapid response times, with an 8 ms pulse eliciting a delay of only about 0.1 ms. According to Prof. Wang, “Our work presents an enticing approach to accessing high-performance functional materials through defect engineering.”
The breakthrough in magneto-superelasticity research offers promising possibilities for the development of advanced materials and devices with significant applications in various industries. This study underscores the importance of defect engineering and controlled transformation processes in enhancing the mechanical properties of materials for future technological advancements.