DISCONTINUOUS PRECIPITATION, COARSENING AND DISSOLUTION OF PHASES IN CU-IN AND CU-SB ALLOYS

The microstructural details of the discontinuous precipitation, coarse ning and dissolution reactions have been studied by optical and scanni ng electron microscopy, and X-ray diffraction in Cu-15 wt.% In and Cu- 5 wt.% Sb alloys. It has been shown that cellular precipitation can no t only occur at grain boundaries but also at matrix/phase boundaries. Secondary cellular reaction (discontinuous coarsening) can start in ea rly stages of ageing. The occurrence of cellular precipitation in the Cu-In alloy follows the Fournelle-Clark mechanism. The dissolution pro cess is discontinuous in the Cu-In alloy and continuous in the Cu-Sb a lloy.