A century of zero expansion

Article Abstract:

A quantum-mechanical explanation for the unusual behaviour of Invar alloys has been presented by Mark van Schilfgaarde, Igor Abrikosov and Borje Johansson. Invar alloys are used in temperature sensitive devices and in shadow masks for television and computer screens. Richard Weiss first proposed the 2gamma-state model which gives a satisfactory explanation for the Invar phenomenon. The magnetic states are further illuminated by including non-collinear spin ordering in the simulation.

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Origin of rubber-like behaviour in metal alloys

Article Abstract:

It is known that some metal alloys, when accompanied by martensite ageing, exhibit rubber-like behaviour and can be deformed, although the origin of such behaviour and of the effect of martensite ageing remains unclear. A new study shows that the change is due to atomic rearrangement within the same sublattice of the ordered martensite and not due to changing degrees of long-range order. Details of the experiment are presented.

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Bismuth embrittlement of copper is an atomic size effect

Article Abstract:

Embrittlement by the segregation of impurity elements to grain boundaries is one of a small number of phenomena that can lead to metallurgical failure by fast fracture. The different ways in which minute traces of bismuth in copper cause ductile metal to fail in a brittle manner is explored.

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