Dehydrogenation During Annealing or Continuous Heating of a Hydrogen-Charged Alloy Based on Titanium Aluminide
- PDF / 1,007,466 Bytes
- 6 Pages / 594 x 792 pts Page_size
- 25 Downloads / 195 Views
669.2.017:620.18
DEHYDROGENATION DURING ANNEALING OR CONTINUOUS HEATING OF A HYDROGEN-CHARGED ALLOY BASED ON TITANIUM ALUMINIDE A. G. Illarionov,1 O. G. Khadzhieva,2 and E. D. Merson3 Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 17 – 22, July, 2020.
Titanium alloy VTI-4 based on orthorhombic titanium aluminide Ti2AlNb is studied in the initial condition and after charging with hydrogen to different concentrations. The kinetics and the rate of hydrogen release from the hydrogen-charged alloys during a 30-min hold at 900°C in a flow of a high-purity inert gas (argon) is analyzed. The curves obtained by differential scanning calorimetry and thermal gravimetric analysis are plotted under continuous heating to 1200°C in the inert argon atmosphere at a rate of 20 K/min. The microstructure of the alloy is studied.
Key words: alloy based on orthorhombic titanium aluminide, hydrogen-charged condition, hot extraction of hydrogen in an inert gas flow, dehydrogenizing annealing, continuous heating, thermal gravimetric analysis, B2 Û A2 transition.
charged with hydrogen for raising the ductility are not exhaustive [17, 18]. Such data may be needed for designing the temperature and time parameters of THT for alloys of the type in question. The aim of the present work was to study the processes of dehydrogenation in commercial hydrogen-alloyed O-alloy VTI-4 under isothermal conditions and under heating in inert and air atmospheres.
INTRODUCTION Alloys based on orthorhombic titanium aluminide Ti2AlNb (O-alloys) are advanced refractory materials with operating temperatures up to 700°C [1, 2], which may contain b-(B2), a2-, and O-phases [3, 4]. Intermetallic titaniumbase alloys are not used much in articles produced by deformation due to their limited process ductility [5, 6]. The process ductility of titanium alloys including intermetallic ones may be raised by using hydrogen technologies [7 – 9], thermohydrogen treatment (THT) in particular [10], which involves reversible alloying with hydrogen. Being a b-stabilizer [11], hydrogen improves the stability of the most ductile b-solid solution in the structure and lowers the temperature of the transition of O-alloys into the b-range [12, 13]. In the final stages of the THT, the O-alloy should be dehydrogenated to a hydrogen concentration safe for operation. The main method for removing hydrogen from titanium alloys is vacuum annealing [14, 15]. However, other methods like hot extraction in a gas flow are also possible [16]. Published data on the development of hydrogen removal from O-alloys 1 2 3
METHODS OF STUDY We studied alloy VTI-4 with chemical composition (in at.%) 24.3Al, 24.8NB, 1.0Zr, 1.4V, 06Mo, 0.3Si, the remainder Ti. To study the central part of an ingot from alloy VTI-4, we cut cylindrical samples with diameter 20 mm. The samples were first charged with hydrogen to obtain three different hydrogen concentrations. The charging was conducted in a Sieverts device, the operating principle of which is described in [19], at a hydrogen pressu
Data Loading...
