Search

The effect of hydrostatic pressure on the martensitic transformation and magnetocaloric properties of MnNi0.88GeV0.12 alloy is studied in detail. X‐ray diffraction at room temperature shows that the alloy has a single hexagonal Ni2In‐type structure. The phase transition temperature moves to the low‐temperature region with the increase in hydrostatic pressure. Under the external magnetic field of 15 kOe, the hydrostatic pressure driving rates dTM/dP and dTA/dP are 60.25 and 65.25 K GPa−1, respectively, which indicate that the applied pressure expands the working temperature range of magnetic refrigeration. A magnetic entropy change ΔS of −4.8 J kg−1 K−1 is obtained in the external magnetic field of 15 kOe under ambient pressure. The peak value of |ΔS| is increased to 5.6 J kg−1 K−1 under hydrostatic pressure, which is closely related to the structural change of the alloy. [ABSTRACT FROM AUTHOR]

The inhomogeneity of the Curie temperature in large-sized LaFe 13−x−y Co x Si y C 0.15 alloys is studied. The Curie temperature of the large-sized LaFe 13−x−y Co x Si y C 0.15 alloys shows a decreasing tendency from the edge to the sub-edge region of the alloy, while the Curie temperature of the small-sized sheet-shaped LaFe 11.2 Co 0.5 Si 1.3 C 0.15 alloy is same in different regions. Besides, chemical analysis shows that the Co and Si content reveals a decreasing tendency from the edge to the sub-edge region in large-sized alloys as well, which may be attributed to the segregation of Co and Si element during slow solidification in large-sized LaFe 13−x−y Co x Si y C 0.15 alloys. So it can be inferred that the segregation of Co and Si could result in the inhomogeneity of Curie temperature in large-sized LaFe 13−x−y Co x Si y C 0.15 alloys. Moreover, both the experiment and the calculation find that the mixed usage of the inhomogeneous LaFe 13−x−y Co x Si y C 0.15 alloys will reduce the maximum magnetic entropy change, which needs more attention in industrial application of La(Fe 1−x Si x ) 13 based alloys. [ABSTRACT FROM AUTHOR]