Title :
Formation and magneto-structural properties of the new Nd3 Fe29-xWx intermetallic phase
Author :
Sanchez, Jose L. ; Neiva, A.C. ; Marques, J.M. ; Missell, F.P. ; De Amorin, H. Salim ; Domingues, P.H. ; Amaral, M.R., Jr.
Author_Institution :
Lab. de Magnetismo, Havana Univ., Cuba
fDate :
9/1/1997 12:00:00 AM
Abstract :
This work reports the existence of the new ternary phase Nd3 Fe29-xWx (monoclinic, prototype Nd3 (Fe,Ti)29), opening the perspective of a W-stabilized family of compounds. Alloys with starting composition Nd3Fe 27.5W1.5 were prepared by argon arc melting from pure elements. As-cast ingots were wrapped in tantalum foils and annealed at 1100°C during three weeks followed by quenching in water. The homogeneous region of the best sample was characterized by structural and magnetic measurements. X-ray diffraction patterns were analyzed by the Rietveld method. For the 3:29 structure the space group A2/m was successfully assumed. The analysis shows that Nd3(Fe,W)29 is the main phase (73 wt.%) with lattice parameters a=10.615(2) Å, b=8.588(2) Å, c=9.754(2) Å and β=96.74(1)0. It co-exists with Nd2(Fe,W)17 (25 wt.%) and α-(Fe,W) (2 wt.%). The thermomagnetic curve of the specimens shows well defined transitions at 72°C and 123°C, which we attribute to the 2:17 and 3:29 phases, respectively. The composition of the 3:29 compound, measured by EDAX analysis, is Nd10.1Fe85.6W4.3. The average composition of the homogeneous region, calculated from the composition (measured by EDAX analysis) and weight fractions (calculated by Rietveld analysis of the XRD patterns) of the phases, is Nd10.1 Fe86.0W3.9. In addition, a small amount of α-(Fe,W) is detected. The saturation magnetization was estimated as 102 emu/g. The temperature dependence of the saturation magnetization and AC susceptibility are reported. The latter shows a magnetic anomaly at 259 K which suggests the existence of a spin reorientation transition
Keywords :
Curie temperature; X-ray diffraction; annealing; ferromagnetic materials; iron alloys; lattice constants; magnetic susceptibility; magnetisation; magnetocaloric effects; neodymium alloys; quenching (thermal); spin dynamics; thermomagnetic effects; tungsten alloys; 1100 degC; 123 degC; 259 K; 3 week; 72 degC; AC susceptibility; Ar arc melting; EDAX analysis; Nd10.1Fe85.6W4.3; Nd10.1Fe86.0W3.9; Nd2(FeW)17; Nd3(FeTi)29; Nd3(FeW)29; Nd3Fe27.5W1.5; Nd3Fe29-xWx intermetallic phase; Rietveld method; Ta foils; W-stabilized family of compounds; X-ray diffraction patterns; XRD patterns; composition; homogeneous region; lattice parameters; magnetic anomaly; magnetic measurements; magneto-structural properties; monoclinic prototype Nd3(Fe,Ti)29; quenching; saturation magnetization; space group; spin reorientation transition; structural measurements; temperature dependence; ternary phase; thermomagnetic curve; transitions; weight fractions; Annealing; Argon; Iron alloys; Magnetic analysis; Magnetic properties; Magnetic variables measurement; Neodymium; Pattern analysis; Prototypes; Saturation magnetization;
Journal_Title :
Magnetics, IEEE Transactions on
