Permanent Magnets based on Fe-Pt Alloys. P.D. Thang, E. Brück, K.H.J. Buschow, F.R. de Boer. Financial support by STW. Introduction Permanent magnets, motivation Experimental Sample preparation, analysis techniques Results Structure, magnetic and mechanical properties
Permanent Magnets based on Fe-Pt Alloys
P.D. Thang, E. Brück, K.H.J. Buschow, F.R. de Boer
Financial support by STW
Permanent magnets, motivation
Sample preparation, analysis techniques
Structure, magnetic and mechanical properties
(DYNA Dental Engineering B.V.)
- Arc-melting the pure elements (3N) in Ar
- Casting to cylinder, disc
- Homogenisation (as-quenched sample):
1325C/1h, under Ar + quenching in water fcc phase.
- Ageing (aged sample):
500-700C + quench in water fct phase.
Tensile strength: tensometer
Magnetic properties: hysteresis-loop
and … SANS
Microstructure analysis: TEM ...
Optimal hard-magnetic properties for Fe60Pt40 aged at 625C, 1h:
Br = 0.97 T, BHc = 294 kA/m, (BH)max = 118 kJ/m3
625°C, 1h: 2-5 nm
as-quenched: 1-3 nm
Fct particle size increases during the ageing.
Fct nano-size observed.
Degree of atomic order increases during the ageing.
as-quenched: 1 nm
625°C,12h: 1-3 nm
625°C,24h: 3-8 nm
625°C,48h: 8-16 nm
mn = 1.674710-24 g
n = 9.6628610-27 J/T
q = 0, 1/2 = 624 s
- Scattering from the atomic nucleus
- Magnetic scattering
- 10 Å 102 Å
- Domain and particle size
q = kf - ki
I(q,) = A(q) + B(q)sin2(/2)
B = 0 (virgin)
B = 1.8 T (in field)
B removed (remanent)
SANS dominated by randomly
oriented magnetic domains: monodisperse model
SANS dominated by particles with different magnetisation: polydisperse model
Correlation length 105 nm
(TEM: fct particles 3-8 nm)
M = 0.5 at. % Nb and 0.25 at. % Al.
Good thermal stabilisation.
Suitable for biomedical applications, e.g. denture retention.
High coercivity: correlated with the atomic order in the fcc/fct
structures and the fct grain growth.
High remanence: originated by the exchange coupling of the
soft fcc phase with the nano-sized hard fct phase.