COMPUTER-MODELED DEFORMATION MECHANISM MAPS FOR HOT UNIAXIALLY PRESSED BI-2223 SUPERCONDUCTOR

A deformation mechanism map represents the densification behaviour of a green powder body. A map is created by evaluating the rate-equations for five types of densification mechanisms: yield, boundary diffusion , volume diffusion, power-law creep, and Nabarro-Herring creep. These rates are summed where appropriate and integrated to give the density at a given pressure, temperature and time; this can then be plotted on a map. Such maps have been created for hot-pressed Bi-2223, using the HIP 6.0 computer software. Four temperature-density deformation maps were created at different pressing pressures and for two types of powd er: a solid-state reacted powder and a pyrolysed organic precursor pow der. The resulting maps are compared and discussed in relation to a se t of experimental results.