Mechanical alloys in the Ti–B–H system: Influence of dispersion and alloying by boron upon thermal stability of hydride phases

Abstract

Influence of dispersion and alloying by boron upon thermal stability and decomposition temperature of hydride phases of mechanical alloys of the Ti–B–H system that were derived in the conditions of high-energy ball milling either of (TiH 1.9 + 9 wt.% B + 13 wt.% Ti) and (TiH 1.9 + 50 wt.% TiB 2) mixtures (50 h milling, rotation speed 1000 rpm) or of (TiH 1.9 + 40 wt.% B) and (TiH 1.9 + 50 wt.% TiB 2) mixtures (20 milling, rotational speed 1630 rpm) has been studied employing scanning electron microscopy, X-ray diffraction analysis, and thermal desorption spectroscopy. It has been established that, dispersion and boron additives to the TiH 1.9 powder followed by mechanical treatment influence thermal stability of the hydride. Mechanical milling the (TiH 1.9 + 9 wt.% B + 13 wt.% Ti) mixture for 50 h in argon causes decreasing the decomposition temperature of a Ti(B,H) x hydride phase by more than 300° compared with that of the initial TiH 1.9 hydride. Mechanisms of influence of both dispersion and boron alloying upon thermal stability of the TiH 1.9 hydride have been studied.