Enhancement of Damping Capbility of MnCu Alloy by High Magnetic Field

The directionally solidified MnCuNiFe alloy was prepared under high magnetic field. The microstructure, composition distribution, phase transformation behavior and damping capacity of the alloy were studied by means of metallographic microscope, scanning electron microscope, transmission electron microscope, X-ray diffraction, differential scanning calorimetry, thermal expansion analysis and dynamic mechanical analysis. It is revealed that magnetic field has definite effect on the refinement of dendrite microstructure as well as the enrichment of Ni element, and thus induces the occurrence of martensitic transformation at about 300 K. The preferred (111) orientation modulated by high magnetic field, especially the induced fct1 → fcc martensitic transformation, together with the twin boundary relaxation, ensure that the directionally solidified MnCuNiFe alloy prepared under high magnetic field owns high-damping capacity in a wide-temperature range from 200 K to 320 K.