Sintering of P/M Nb-TiB_2 Alloys

摘要

In this paper, we have investigated the possibility of using TiB_2 particles to promote reinforcement strengthening in niobium. Niobium obtained from the HDH process and TiB_2, both in the powdered form, were mixed, cold pressed and sintered in high vacuum in temperatures ranging from 1300 to 1900℃ for 4 hours. In this paper we present and discuss the results concerning the microstructural evolution during high-vacuum sintering of niobium with additions of TiB_2 up to 2 wt-%. Aspects related to phase stability and chemical composition of the resulting alloys will be discussed. Results show that dissolution of TiB_2 particles becomes significant above 1400℃. After sintering at 1900℃, the smaller TiB2 particles are fully dissolved whereas the larger ones are partially dissolved. Dissolution of TiB_2 particles occurs with the formation of Nb-Ti solid solution and NbB phases.