Thus, it is expected that the solid solution aluminum precipitated in the matrix during the HIP, changing the matrix back to the close state to pure Cu. This hypothesis is supported by the results of the elec- trical resistivity measurements shown in Fig. 7 , in which the close resistivity of pure Cu (OFC) and the alloy after MA of 43 hrs mea- sured at 77 K implies similar matrix purity of the two materials