Long Hou

Large reversible magnetocaloric effect in RE2Cu2In (RE = Er and Tm) and enhanced refrigerant capacity in its composite materials

The magnetic properties and magnetocaloric effect (MCE) in RE2Cu2In (RE = Er and Tm) compounds and its composite materials have been investigated. A large reversible MCE is observed at around their own Curie temperature of T C ~ 39.4 and 31.6 K for Er2Cu2In and Tm2Cu2In, respectively. Under a magnetic field change of 0–7 T, the maximum values of magnetic entropy change () are estimated to be 18.4 and 18.2 J kg−1 K−1 for Er2Cu2In and Tm2Cu2In, respectively. A table-like MCE at a temperature of 20–50 K and enhanced refrigerant capacity (RC) are realized in the Er2Cu2In–Tm2Cu2In composite materials. For magnetic field changes of 0–5 and 0–7 T, the maximum improvements of RC reach 32% (12%) and 28% (14%), in comparison with that of the individual compound Er2Cu2In (Tm2Cu2In), respectively. The excellent MCE properties make the RE2Cu2In composite materials attractive for low-temperature magnetic refrigeration.

Excellent magnetocaloric properties in RE2Cu2Cd (RE = Dy and Tm) compounds and its composite materials.

The magnetic properties and magnetocaloric effect (MCE) of ternary intermetallic RE2Cu2Cd (RE = Dy and Tm) compounds and its composite materials have been investigated in detail. Both compounds undergo a paramagnetic to ferromagnetic transition at its own Curie temperatures of TC ~ 48.5 and 15 K for Dy2Cu2Cd and Tm2Cu2Cd, respectively, giving rise to the large reversible MCE. An additionally magnetic transition can be observed around 16 K for Dy2Cu2Cd compound. The maximum values of magnetic entropy change (−ΔSMmax) are estimated to be 17.0 and 20.8 J/kg K for Dy2Cu2Cd and Tm2Cu2Cd, for a magnetic field change of 0–70 kOe, respectively. A table-like MCE in a wide temperature range of 10–70 K and enhanced refrigerant capacity (RC) are achieved in the Dy2Cu2Cd - Tm2Cu2Cd composite materials. For a magnetic field change of 0–50 kOe, the maximum improvements of RC reach 32% and 153%, in comparison with that of individual compound Dy2Cu2Cd and Tm2Cu2Cd. The excellent MCE properties suggest the RE2Cu2Cd (RE = Dy and Tm) and its composite materials could be expected to have effective applications for low temperature magnetic refrigeration.

Correlation between microstructures and mechanical properties in Ni-rich Ni–Mn–Ga high-temperature shape-memory alloys

ABSTRACT Microstructures and mechanical properties of polycrystalline and single-crystalline Ni55+xMn25Ga20−x (x = 1, 2, 3) alloys are investigated. The alloys exhibit a single martensite phase for x = 1, and two phases containing tetragonal martensite phase and face-centered γ phase for x = 2 and 3. The appearance of γ phase can apparently raise the strength and plasticity of the alloys. Moreover, single crystals show better mechanical properties compared with the polycrystals with the same composition. Furthermore, a kind of net-like γ phase is observed in directionally solidified Ni58Mn25Ga17 single crystal. This alloy exhibits excellent plasticity due to that the crack propagation is seriously hindered by the plastic net-like γ phase.

Control of dendrite growth by a magnetic field during directional solidification

In this work, the alignment behavior of three kinds of dendrites (Al3Ni, alpha-Al and Al2Cu dendrites) with a remarkable crystalline anisotropy during directional solidification under an axial magnetic field is studied by the EBSD technology. Experimental results reveal that the magnetic field is capable of tailoring the dendrite alignment during directional solidification. Further, based on the crystalline anisotropy, a method to control the dendrite alignment by adjusting the angle between the magnetic field and the solidification direction is proposed. Copyright (C) EPLA, 2016