Published online by Cambridge University Press: 31 January 2011
Kinetics of congruent ordering in Cu3Au at 350 °C was investigated by means of a three-dimensional atom probe. This instrument, called a Tomographic Atom Probe (TAP), enables atomic resolution images of a small volume (10 × 10 × 100 nm3) of the material reconstructed in the three dimensions of space. The time evolution of ordered domains at 350 °C shows that a t1/2 law is followed as soon as 5 min. For this aging time, the nucleus diameter is close to 1.7 nm. This scaling law was observed even before domains came into contact (t = 50 min). Competitive growth was observed to start as soon as 5 min. The number density was observed to decrease rapidly up to t = 50 min. A slower decrease was observed when domains begin to impinge. Experimental conditions and requirements as well as advantages of TAP as compared to HREM for the study of ordering are discussed in detail.