Abstract
Doping of interstitial elements B or C into a BCC-type Ti 25 V 35 Cr 40 alloy to raise effective desorption hydrogenation capacity was investigated. Ti 25 V 35 Cr 40 M x alloys (M = B or C and x = 0, 0.1, 1, or 5) were prepared by arc-melting followed by homogenization treatment. X-ray diffraction shows that the as-cast specimens have a BCC structure, but they contain some amount of precipitates that increases with the doping concentration of B and C. Doping-induced precipitates can be greatly eliminated by annealing treatment at 1200 °C, indicating that B or C might have been partially dissolved into the interstitial sites in the BCC lattice of matrix phase of specimens. With the doping of C, the second plateau pressure of annealed specimens in the PCI curves at T = 30 °C significantly increases with the amount of C, but the maximum hydrogenation capacity is reduced. On the other hand, the second plateau pressure and maximum hydrogenation capacity are only slightly affected by the B doping. Under optimum doping conditions, the effective hydrogen desorption capacities are increased from 0.80 H/M of the sample without doping to 0.86 H/M and 0.87 H/M for Ti 25 V 35 Cr 40 B 1 and Ti 25 V 35 Cr 40 C 0.1 , respectively. The improvement might be ascribed to the increase in second plateau pressure caused by less stable hydrogen atoms at the lattice sites of Ti 25 V 35 Cr 40 containing interstitial B or C. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.