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 studied by means of atom probe field ion microscopy (APFIM). The morphology of the lamellar microstructure and the growth kinetics of the decomposition reaction have been investigated by optical and scanning electron microscopy (LM, SEM). A back-polishing method for transmission electron 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. APFIM results of the chemical composition across the interfaces are reported. Based on the APFIM results it is possible to improve the theoretical description of the concentration profiles given by the models of Cahn and Hillert.