AN APFIM TEM INVESTIGATION OF THE DISCONTINUOUS PRECIPITATION IN A NI-IN ALLOY/

Discontinuous precipitation (DP) in a Ni-7.5at%In alloy has been studi ed by means of atom probe field ion microscopy (APFIM). The morphology of the lamellar microstructure and the growth kinetics of the decompo sition reaction have been investigated by optical and scanning electro n microscopy (LM, SEM). A back-polishing method for transmission elect ron microscopy (TEM) has been developed to prepare APFIM specimens in a systematic manner, so that different interfaces can be positioned in the tip apex for subsequent analysis of their chemical composition. A PFIM results of the chemical composition across the interfaces are rep orted. Based on the APFIM results it is possible to improve the theore tical description of the concentration profiles given by the models of Cahn and Hillert.