PHASE-FORMATION AND KINETICS IN MELT-SPUN AND SPUTTERED ALLOYS ALONG THE LINE CU40NI60-CU30NI45SN25

The ternary system Cu-Ni-Sn includes intermetallic phases of D0(19), 2 H and DO3 structure. These have some interesting properties for future mechanical investigations. Recently, Cu-Ni-Sn alloys were investigate d to understand the process of phase formation and to learn how to pro duce single-phase and well defined multi-phase material. The results s how complex phase formation and leave some open questions, especially concerning the low-temperature range. The present investigation uses s puttered and melt-spun Cu-Ni-Sn alloys to get information about the in fluence of different preparation methods. Isothermal and dynamic X-ray diffraction measurements together with TEM investigations reveal info rmation about the phase diagram and kinetics of phase formation down t o 500 degrees C. Proposed equilibrium diagrams are presented: a vertic al section along Cu40Ni60-Cu30Ni45Sn25 and isothermal cuts across the Sn-poor side of the ternary Cu-Ni-Sn diagram. The precipitation of int ermetallic phases in supersaturated ternary solid solutions is shown t o be a two-step process. (C) 1996 Elsevier Science Ltd.