The determination of Curie temperature of amorphous Fe-Nb-B alloys by DSC under magnetic field

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Scripta Metallurgica; (United States)

DOI:https://doi.org/10.1016/0956-716X(91)90105-A· OSTI ID:5279116

Leu, M S; Lin, C S ^[1]; Lin, S T ^[2]

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1. Material Research Lab., Industrial Technology Research Inst., Chutung, 31015 Hsinchu (TW)
2. Dept. of Physics, National Cheng Kung Univ. (TW)

Differential scanning calorimetry (DSC) is a convenient and accurate method for measuring magnetic Curies temperature (Tc) in terms of the observation that the specific heat has a visible variation in the transition. Already known is the fact that when heat is added to the magnetic alloys, it partially contributes to the lattice and the electronic specific heat. The remainder disorders the spins, which contributes to magnetic specific heat. The number of disordered spins per degree of temperature rise increases with the temperature in accordance with the appropriate Brillouin function, and reaches a maximum value in the vicinity of the Curie temperature, where the magnetization is decreasing precipitously. The changes in magnetization accompanying the changes in magnetic enthalpy give rise to a specific heat anomaly around the Curie point, and the magnetic enthalpy {Delta}Hm is schematically shown by the hatched area. Some alloys, e.g., amorphous (FeO.9Nb0.1)80B20 (nominal composition), have a magnetic transition involving a very small enthalpy change which is difficult to detect from DSC measurement. An improved method presented in this paper is to apply an axial magnetic field on samples during the DSC scanning process; the magnetic enthalpy of the Curie transition is amplified and a sharp Tc transition is easily determined.

• OSTI ID: 5279116
• Journal Information: Scripta Metallurgica; (United States), Journal Name: Scripta Metallurgica; (United States) Vol. 25:1; ISSN 0036-9748; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
AMORPHOUS STATE
BORON ALLOYS
CHEMICAL COMPOSITION
CURIE POINT
INTERMETALLIC COMPOUNDS
IRON ALLOYS
MAGNETIC FIELDS
NIOBIUM ALLOYS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE