The silver-based heusler alloys
1959; Taylor & Francis; Volume: 4; Issue: 42 Linguagem: Inglês
10.1080/14786435908243269
ISSN0031-8086
Autores Tópico(s)Magnetic Properties of Alloys
ResumoAbstract Abstract The structures of some fifty alloys of silver, manganese, and aluminium have been studied with a view to explaining the magnetic properties of these alloys. Approximate equilibrium diagrams were made at 400°c and 660°c, and the alloys were also examined after quenching from the latter temperature. It follows from this examination that ferromagnetism in alloys in the vicinity of the atomic composition AgsMnAl is not associated with any equilibrium product, but arises from a finely dispersed nucleation structure, which grows during ageing in to a Widmanstätten pattern and eventually transforms above the Curie point into β-manganese, rendering the alloy non-ferromagnetic. The ferromagnetic precipitate was extracted and identified by electron diffraction as having an ordered hexagonal structure with a = 2·94 Å, c/a = 1·61. This result is used to discuss the variation of magnetization with temperature in these alloys, and also the origin of their very high ooercivities. A brief discussion of the valency of manganese in these structures is also included.
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