The role of boron in the mechanical milling of titanium-6percent aluminium-4percent vanadium powders

摘要

The reduction in grain size of a metal can lead to significant improvement in mechanical properties. Mechanical alloying (MA) with a second phase is a possible route to producing fine-grained, particulate reinforced material. This study describes the microstructural development of Ti-6percentAl-4percentV milled with increasing concentrations of boron Mechanical milling of Ti-6percentAl-4percentV powder produces a nanocrystalline material. MA of Ti-6percentAl-4percentV with boron results in the alloying of the two to form either a boride or an amorphous phase when the local concentration of boron is approx 50 at.percent. During milling, the boron tends to remain near to its original particle form and in these boron-rich regions TiB is formed. Beyond these regions small amounts of boron (a few at.percent) mix with the titanium matrix and reduce further the grain size of the titanium. An increase in the global concentration of boron increases the volume fraction of boride produced.