The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 all...The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 alloy, inhomogeneous in the as-quenched state, crystallized after annealing at 948 K for 0.5 h and consisted of Nd2Fe14B-type, Fe2B and paramagnetic phases. The rapidly solidified Fe64Co5Nd6Y6B19 alloy contained the Nd2Fel4B-type and paramagnetic phases. The annealing of the bulk Fe67CosNd3Y6B19 alloy at 948 K for 0.5 h led to hard magnetic properties. However, the bulk Fe64Co5Nd6Y6B19 alloy exhibited good hard magnetic properties directly after preparation.展开更多
The relationship between topography,thermo magnetic and mechanical properties in the as-cast Gd75Ge15Si5Pr5 alloy was studied.Atomic force microscopy investigations accompanied by micrograph analysis confirm dual phas...The relationship between topography,thermo magnetic and mechanical properties in the as-cast Gd75Ge15Si5Pr5 alloy was studied.Atomic force microscopy investigations accompanied by micrograph analysis confirm dual phase nature(observed as dark and bright phase)of the investigated material.The mechanical properties studies performed with respect to the Oliver-Pharr procedure show that the average instrumental hardness,Young’s modulus and elastic deformation energy to total energy ratio equal 905 HV and 596 HV,131 and 91 GPa,40%and 45%for the dark and bright phase,respectively.The Curie point defined as inflection point on the magnetization versus temperature curve M(T)recorded in zero-field cooled mode equals 283 K.From the law of approach to magnetic saturation the temperature dependence of effective anisotropy constant Keff was calculated in ferromagnetic region.It is also stated that the minimum observed on thermomagnetic M(T)characteristic at 100 K is associated with Keff(T)dependence.展开更多
Polycrystalline Ni50Mn25Ga20Gd5(at%)magnetic shape memory alloy was investigated in the asprepared state and after annealing at 1430 K for 3 h.Microstructural analysis reveals dual-phase nature of the material with su...Polycrystalline Ni50Mn25Ga20Gd5(at%)magnetic shape memory alloy was investigated in the asprepared state and after annealing at 1430 K for 3 h.Microstructural analysis reveals dual-phase nature of the material with substantial distinction between Gd-rich and Gd-poor phases.Magnetic measurements performed in wide range of temperatures confirm reversible martensitic transformation in the annealed sample undergoing close to the room temperature.When it comes to the magnetic transition,the Curie temperature of the investigated alloy remains approximately unchanged at 370 K.Topography investigations conducted on the atomic force microscope in contact mode allow to measure 8 mm difference between minimum and maximum point of the martensite profile.The results from a series of nanoindentation tests show that hardness of the Gd-rich phase is 23%-35%higher than hardness of the Gd-poor phase,depending on the annealing state.展开更多
基金supported by the grants PBZ-MEiN/01/2006/09 (M. Hasiak)PBZ-KBN-115/T08/04 (J. Kaleta)
文摘The phase composition, magnetic properties i.e. coercivity and the magnetic polarization at room temperature for the bulk Fe67Co5Nd3Y6B19 and Fe64Co5Nd6Y6B19 alloys were studied. The bulk amorphous Fe67CosNd3Y6B19 alloy, inhomogeneous in the as-quenched state, crystallized after annealing at 948 K for 0.5 h and consisted of Nd2Fe14B-type, Fe2B and paramagnetic phases. The rapidly solidified Fe64Co5Nd6Y6B19 alloy contained the Nd2Fel4B-type and paramagnetic phases. The annealing of the bulk Fe67CosNd3Y6B19 alloy at 948 K for 0.5 h led to hard magnetic properties. However, the bulk Fe64Co5Nd6Y6B19 alloy exhibited good hard magnetic properties directly after preparation.
文摘The relationship between topography,thermo magnetic and mechanical properties in the as-cast Gd75Ge15Si5Pr5 alloy was studied.Atomic force microscopy investigations accompanied by micrograph analysis confirm dual phase nature(observed as dark and bright phase)of the investigated material.The mechanical properties studies performed with respect to the Oliver-Pharr procedure show that the average instrumental hardness,Young’s modulus and elastic deformation energy to total energy ratio equal 905 HV and 596 HV,131 and 91 GPa,40%and 45%for the dark and bright phase,respectively.The Curie point defined as inflection point on the magnetization versus temperature curve M(T)recorded in zero-field cooled mode equals 283 K.From the law of approach to magnetic saturation the temperature dependence of effective anisotropy constant Keff was calculated in ferromagnetic region.It is also stated that the minimum observed on thermomagnetic M(T)characteristic at 100 K is associated with Keff(T)dependence.
文摘Polycrystalline Ni50Mn25Ga20Gd5(at%)magnetic shape memory alloy was investigated in the asprepared state and after annealing at 1430 K for 3 h.Microstructural analysis reveals dual-phase nature of the material with substantial distinction between Gd-rich and Gd-poor phases.Magnetic measurements performed in wide range of temperatures confirm reversible martensitic transformation in the annealed sample undergoing close to the room temperature.When it comes to the magnetic transition,the Curie temperature of the investigated alloy remains approximately unchanged at 370 K.Topography investigations conducted on the atomic force microscope in contact mode allow to measure 8 mm difference between minimum and maximum point of the martensite profile.The results from a series of nanoindentation tests show that hardness of the Gd-rich phase is 23%-35%higher than hardness of the Gd-poor phase,depending on the annealing state.
