TEXTURE DEVELOPMENT IN AG-NI POWDER COMPOSITES

Both theoretical and experimental studies of texture development in two-phase materials are presented. Finite-element techniques are used in order to characterize the strain and rotation sharing between the two phases. Different volume fractions of Ag-Ni powder composites were simulated in two-dimensional deformation until a von Mises equivalent strain of 1.25. Some average parameters were obtained and used to interpret texture results. 25%Ag-Ni, 50%Ag-Ni and 75%Ag-Ni powder composite samples were deformed in free compression and the texture measured every 20% strain. The texture evolution for Ag shows a saturation due to high internal rotation of this phase. The Ni texture shows a continuous strengthening until it even surpasses the strength of the Ag phase at high deformations. Also some textures for 50%Ag-50%Ni composites deformed by rolling are shown. The Ni texture strength is also shown to be higher than the Ag texture at high deformations. This phenomenon is explained by the finite-element simulations and strain path changes. The two phases deform at different paces, which is beneficial for Ag as a softer phase, but they also spin around one another with different rate, which happens to be beneficial for Ni phase strengthening its texture.