| In the present study, tensile fracture behavior of Cu-(9-x)Ni-xMn-6Sn alloys was examined as functions of aging time and an amount of Mn addition, based on the detailed SEM micrographic and fractographic observations. Discontinuous precipitation colonies, consisted of equilibrium α and γ phases, were observed around the grain boundary areas, and the amount of these colonies increased with increasing Mn addition and aging time. For those alloys where the Mn addition was restricted below 1%, typical fracture mode was intergranular dimpled rupture. In Cu-6Ni-3Mn-6Sn alloys, on the other hand, first cracks occur at discontinuous precipitation colonies and, the cracks appear to coalesce through void sheeting mechanism with the presence of strong shear stress between cracks. |
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