The effect of heat treatment on the
first hydrogenation of body
centred cubic (BCC) Ti52V12Cr36 alloy
was investigated. It was found that, after a 1 week heat treatment
at 1273 K, BCC phase abundance was greatly reduced by heat treatment.
The crystal structure changed from BCC to a complex multiphase pattern
of BCC phase, C15-type Laves phase, and α-Ti. The network of
the α-Ti phase was broader after heat treatment. The heat treatment
eliminated the incubation time of the first hydrogenation and improved
the kinetics, but the total hydrogen capacity was reduced by 30%.
Specific aluminium consumption in the production of ferro-titanium through alumino-thermic reduction is usually far above the stoichiometric requirement, in industrial processes. A thermochemical analysis of the process in an industrial operation was carried out to explore this phenomenon. Aluminium was lost as volatile oxides. Entrapment of titanium in the slag layer led to lower recoveries and higher specific aluminium consumption. Oxidation of aluminium by atmospheric oxidation contributed to an increase in the volume of slag produced. The higher the volume of slag, the greater the entrapment of metal in slag. Segregation between aluminium and ore during charging into the reactor vessel led to an increase in the volume of the slag produced since the segregation prevented chemical reaction between the ore and the metal and the latter was predominantly oxidised by air. Trials were conducted by modifying the charge proportion to control the volume of slag produced. This resulted in a decrease in specific aluminium consumption by 100 kg per tonne of titanium produced.Dans les procédé s industriels, la consommation spé cifique d'aluminium lors de la production du ferrotitane par ré duction aluminothermique est habituellement bien au-delà de l'exigence stoechiomé trique. On a effectué une analyse thermochimique du procédé dans une opé ration industrielle afin d'explorer ce phénomè ne. L'aluminium se perdait sous forme d'oxydes volatiles. Le pié geage du titane dans la couche de laitier menait à des ré cupé rations plus faibles et à une consommation spé cifique plus élevé e d'aluminium. L'oxydation de l'aluminium par oxydation atmosphé rique contribuait à une augmentation du volume de laitier produit. Plus le volume de laitier est grand, plus grand est le pié geage du mé tal dans le laitier. La sé gré gation entre l'aluminium et le minerai lors du chargement dans la cuve du ré acteur menait à une augmentation du volume de laitier produit puisque la ségré gation empê chait la ré action chimique entre le minerai et le mé tal et ce dernier était oxydé e par l'air d'une manière pré dominante. On a effectué des essais en modifiant la proportion de la charge pour contrô ler le volume de laitier produit. Ceci a eu pour ré sultat une diminution de la consommation spé cifique d'aluminium de 100 kg par tonne de titane produit.
The addition of 4 wt% Zr to Ti52V12Cr36 alloy was carried out in two different ways: arc-melting or ball-milling. The cast alloy showed rapid hydrogen absorption up to 3.6 wt% of hydrogen capacity within 15 min. Ball milling this sample worsened the kinetics, and no hydrogen absorption was registered when milling was carried out for 30 or 60 min. When zirconium is added by ball-milling, the kinetic is slower than that when addition is by arc-melting. This is due to the fact that when added by milling, zirconium does not form a ternary phase with Ti, V, and Cr but instead is just dispersed on the particles’ surface.
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