Microstructure of spark-plasma sintered TiB2-Cu nanocomposites

The goal of this study is to investigate the evolution of microstructure of TiB₂ -60 wt.% Cu nanocomposite and titanium diboride nanoparticles behavior during spark-plasma sintering. One of the current problems facing material science is the production of bulk materials with fine nano-level microstructure. Methods of mechanical alloying and mechanical treatment are widespread and well known for making it possible producing a great variety of composite powders with nano-level grains or inclusions. Ti-B-Cu powder mixtures were mechanically treated in high-energy planetary ball mill AGO-2 with stainless steel balls and vials. Balls of 5 mm diameter were used. The powder/balls weight ratio was 1/20 in all experiments. Before milling the vials were pumped and filled with argon to prevent oxidation during processing. To study the connectivity between TiB₂ particles we removed copper matrix from the surface of SPS-compacts by electrochemical etching and formed a layer. X-ray phase analysis shows that this layer consists of titanium diboride as the major phase with small amounts of TiBO₃ probably formed as a result of electrochemical reaction.