Evolution of microstructure and defect structure in L1(0)-ordered manganese aluminide permanent magnet alloys

Defects produced in massively transformed L1(0)-ordered tau -MnAl have been characterized by detailed TEM studies. The defect population in massive ta u -MnAl comprises arrays of overlapping octahedral stacking faults, {111}-c onjugated microtwins, thermal antiphase boundaries and dislocations. The ge nesis of these defects has been attributed to atomic attachment faulting on {111}- and {020}-type facets of the essentially incoherent growth interfac e between the parent and product phases. The features of the defect genesis in T-MnAl are discussed with respect to the role of atomic level processes at solid-state transformation interfaces in general and growth interfaces in massively transforming materials systems in particular. (C) 2001 Elsevie r Science Ltd. All rights reserved.