Accession Number : ADA292796

Title :   Transitions, Defects, and Whiskered Microstructures.

Descriptive Note : Final technical rept. 1 Jul 91-31 Dec 94,

Corporate Author : MINNESOTA UNIV MINNEAPOLIS OFFICE OF RESEARCH AND TECHNOLOGY TRANSFER ADMINIS TRATION

Personal Author(s) : James, Richard ; Kinderlehrer, David ; Luskin, Mitchell

PDF Url : ADA292796

Report Date : 15 FEB 1995

Pagination or Media Count : 10

Abstract : James and Kinderlehrer have given a new theory of magnetostriction. The theory shows excellent agreement with experiment and has motivated new experiments on the relation between domain structure and behavior by Lord and by DeGraef. The theory implies a new mechanism for magnetostriction in Tb(x)Dy(1-x)Fe2 (x near 0.3). It also strongly suggests the existence of materials (termed "magnetomemory" materials by the authors) that would have magnetostrictive strain that is two orders of magnitude larger than the largest produced by current giant magnetostrictive materials. Luskin and his research group have developed an advanced computational model for the dynamics of crystals which undergo a martensitic transformation. They have used this model to compute the development of martensitic microstructure and the propagation of the interface separating the austenitic phase from the martensitic phase, and they have obtained results for the influence of the surface energy and the viscosity on the dynamics. James, Kinderlehrer, Luskin and their collaborators have studied new mechanisms for hysteresis, and have clarified the role of elastic incompatibility, shuffling, kinetics, and microstructure. jg

Descriptors :   *TRANSITIONS, *MAGNETOSTRICTION, *DEFECT ANALYSIS, *WHISKERS(CRYSTALS), MATHEMATICAL MODELS, PROPAGATION, MICROSTRUCTURE, COMPUTATIONS, DYNAMICS, INTERFACES, MATERIALS, COMPOSITE MATERIALS, THEORY, ELASTIC PROPERTIES, COMPATIBILITY, CRYSTALS, AUSTENITE, IRON, KINETICS, VISCOSITY, HYSTERESIS, TRANSFORMATIONS, MARTENSITE, SURFACE ENERGY, TERBIUM, DYSPROSIUM.

Subject Categories : Electricity and Magnetism
      Inorganic Chemistry
      Physical Chemistry
      Laminates and Composite Materials
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE