Shock compression of Ti–B–Cu powder mixtures: Microstructural aspects

Shock compression of Ti–B–Cu powder mixtures at a pressure of 3 GPa was investigated. The reaction between titanium and boron was initiated by the shock wave; however, it was not completed. Short high-energy mechanical milling of the powder mixtures before the shock compression ensured full conversion of titanium and boron to titanium diboride. Due to the geometrical issue of the interaction of the shock wave with the powder sample in a cylindrical ampoule, the outer part of the sample was denser but less uniform in the microstructure than the central part. The central part of the sample showed a nanocomposite structure with even distribution of 100–300 nm grains. The size of grain agglomerates of each of the two phases was not larger than 1 μm. In the outer part Cu and TiB2-enriched areas up to 5–10 μm in size could be found. The observed difference is explained by intensive turbulization and mixing in the central part of the ampoule during shock compression.