Landolt-Börnstein - Group III Condensed Matter

7.2.1.7.2 Permanent magnet properties of Co-Pt alloys as dependent on the preparation technique

Abstract

This chapter provides a survey of magnetic properties of Co-Pt alloys in relation to the preparation techniques. The preparation techniques include casting (CA), aging (AG), homogenization (HG), cold working (CW), annealing (AN), quenching (Q). As-quenched state, twinned grains typical of many fcc crystals are observed. For AG(500,48h), new grains recrystallize from the parent grains, predominantly at grain boundaries during ordering. For AG (600,48h), the general nucleation and growth of the ordered particles as an unresolved mottling are observed or they are obliterated by gross features of the microstructure. X-ray analysis shows that the structure is practically completely ordered. For AG(700-728, 50h), the gross features are suppressed and the Widmanstatten pattern becomes recognizable due to the pressure of ordered plate-like particles lying on (110) matrix planes. For HG(1100, 50h): AG(700,2), superlattice line is visible indicating tetragonal splitting with c/a = 0.982. The ordered precipitates having linear dimensions of ca. 50-100 Å are observed in some particle-clustering by darkfield electron micrograph. The magnetic properties include Br, BHc, and (BH)max. Influence of aging time ta and aging temperature Ta and additional second aging process on the permanent magnet properties of Co0.49Pt0.51 are shown. Demagnetization curves after various double aging procedures for the Co0.49Pt0.51 alloy are also shown.

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Title
7.2.1.7.2 Permanent magnet properties of Co-Pt alloys as dependent on the preparation technique
Book Title
Magnetic Alloys for Technical Applications. Hard Magnetic Alloys
In
7.2.1.7 Magnet alloys with order transformation (Co-Pt and Fe-Pt alloys)
Book DOI
10.1007/b41058
Chapter DOI
10.1007/10028076_30
Part of
Landolt-Börnstein - Group III Condensed Matter
Volume
19I2
Editors
  • H. P. J. Wijn
  • Authors
  • T. Nakamichi
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