Elements In Titanium Alloys Research Articles

Formation of titanium hydride in Ti–6Al–4V alloy

Use of hydrogen as a temporary element in titanium alloys is an attractive approach for enhancing processability, and also for modification of microstructures and thereby improving final mechanical properties. In this article, microstructures, phases and phase transformations in Ti–6Al–4V alloy specimens containing 0.1, 0.3 and 0.5 wt.% hydrogen has been investigated using optical microscopy, XRD and TEM. It was shown that there are fcc δ titanium hydride plates precipitated in the specimens containing hydrogen 0.302 and 0.490 wt.%. Simultaneously, mass orthorhombic martensite α″ has been found in the specimens as well as δ hydride. One eutectoid transformation mechanism from β H to δ hydride and α based on diffusion transformation theory was presented.

Cyclic deformation behaviour of austenitic steels at ambient and elevated temperatures

The aim of the present investigation is to characterise cyclic deformation behaviour and plasticity-induced martensite formation of metastable austenitic stainless steels at ambient and elevated temperatures, taking into account the influence of the alloying elements titanium and niobium. Titanium and niobium are ferrite-stabilising elements which influence the ferrite crystallisation. Furthermore, They form carbides and/or carbonitrides and thus limit the austenite-stabilising effect of carbon and nitrogen. Several specimen batches of titanium and niobium alloyed austenite and of a pure Cr-Ni-steel for comparison were tested under stress and total strain control at a frequency of 5 Hz and triangular load-time waveforms. Stress-strain-hysteresis and temperature measurements were used at ambient temperature to characterise cyclic deformation behaviour. Plasticity-induced martensite content was detected with non-destructive magnetic measuring techniques. The experiments yield characteristic cyclic deformation curves and corresponding magnetic signals according to the actual fatigue state and the amount of martensite. Fatigue behaviour of X6CrNiTil810 (AISI 321), X10CrNiCb189 (AISI 348) and X5CrNi1810 (AISI 304) is characterised by cyclic hardening and softening effects which are strongly influenced by specific loading conditions. Martensite formation varies with the composition, loading conditions, temperature and number of cycles.

Thermohydrogen processing of titanium alloys

Use of hydrogen as a temporary alloying element in titanium alloys is an attractive approach for enhancing processability including working, machining, sintering, compaction, etc., and also for controlling the microstructure and thereby improving final mechanical properties. In this article, the status of the methods and applications of thermohydrogen processing (THP) to titanium alloys is reviewed. Effects of hydrogen alloying on the phases present, their composition, and the kinetics of phase reactions are considered. The effect of hydrogen on the hot workability, composite- and powder-metallurgy-product processing, and microstructure modification of wrought and cast conventional alloys and intermetallics, including production of nanocrystalline structures is discussed. Two recently discovered effects, i.e. hydrogen-induced softening of α titanium and hydrogen-induced hardening of β titanium are also discussed. Thermohydrogen processing has clear advantages in the development of improved microstructures and mechanical properties. In the case of near net shapes it is the only method for significant microstructural modification. It allows energy savings in processing to final products by improving the workability. © 1999 International Association for Hydrogen Energy.

Hydrogen induced microstructural changes in Al-Ti alloys

Among the family of transition metal high temperature alloys, Al-Ti alloys are actively being studied as a result of their attractive combination of elevated temperature properties. These materials derive their excellent strength, ductility, and creep resistance from their refined microstructure and dispersion of Al{sub 3}Ti particulates, in combination with the low solid solubility and low volume diffusivity of Ti in Al. Thermochemical Processing (TCP), or the use of hydrogen at high temperature as a temporary alloying element in titanium alloys, can significantly enhance processability and refine the final microstructure. There are no reports of the transformation of a crystalline structure into a nanocrystalline one by hydrogen charging with high fugacities at room temperature. The objective of this study is to show that hydrogen charging an aluminum titanium alloy with very high fugacities produces a very refined microstructure and may result in a microcrystalline to nanocrystalline transformation.

Literature Survey on Diffusivities of Oxygen, Aluminum, and Vanadium in Alpha Titanium, Beta Titanium, and in Rutile

A survey of diffusion data of interstitial oxygen and of the substitutional elements aluminum and vanadium is presented for alpha and beta titanium. It is based on a survey of literature. Oxygen is an important interstitial element in titanium alloys. Oxygen’s large chemical affinity to titanium is indicated by Ti—O bond energy of 2.12 eV,1 comparable to the Ti—Ti bond energy of 2.56 eV.2 Oxygen is difficult to eliminate completely from titanium, and commercial titanium alloys usually contain from 0.10 to 0.20 wt pct oxygen. Oxygen significantly affects the mechanical properties of titanium alloys1,3 and is sometimes used as an alloying element. The effects of oxygen on phase transformation ,4,5,6 Youngs modulus,7,8 hardness,9,10 fracture toughness,11 and other mechanical properties12 have been amply documented. Aluminum and vanadium are the most frequently used substitutional alloying elements. Aluminum is an alpha stabilizer and vanadium is a beta stabilizer.

Modeling the process of redistribution of alloying elements in titanium alloys in interaction with gas media

Modeling the process of redistribution of alloying elements in titanium alloys in interaction with gas media

Rapid determination of the alloying elements in titanium alloys by inductively-coupled plasma emission spectrometry

Summary The sample (0.1 g) is dissolved in hydrofluoric and nitric acids in a polyethylene beaker. After the hydrofluoric acid has been masked with boric acid, the minor components Al, Sn, Zr, Mo, V, Mn and Si are determined by their atomic emission in the plasma.

Determining the energy of interaction of impurity atoms with dislocations in titanium alloys

Determining the energy of interaction of atoms of alloying elements in titanium alloys by measuring the internal friction, we found that alloying leads to an increase in the energy of interaction. This may explain the higher values of the ultimate tensile strength of alloy VT22 in comparison with that of commercial titanium VT1-0.

Use of emission microspectral analysis to investigate distribution of elements in titanium alloys

Use of emission microspectral analysis to investigate distribution of elements in titanium alloys

Magnetic Properties of Dilute Alloys of Scandium

Previous experiments have shown that small quantities of cerium will induce a spin-compensated state in the d1 elements yttrium and lanthanum. The magnetic susceptibility of scandium alloys with 0.02–2-at.% cerium has been measured over the temperature range of 4°–300°K. No evidence for a spin-compensated state is found. Addition of gadolinium has been shown to polarize the scandium matrix. To study the influence of a heavy rare earth with nonzero orbital angular momentum on the polarization of the scandium matrix a series of dilute dysprosium alloys have been studied. The effect of dysprosium is found to be similar to that of gadolinium. Also the influence of the nonmagnetic alloying elements titanium and thorium on scandium has been investigated in order to separate the various factors affecting the magnetic properties of dilute scandium alloys.

Determination of aluminum, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, tin and vanadium in titanium alloys by atomic absorption spectrometry

An accurate and rapid atomic absorption analysis for the determination of 10 alloying elements in titanium alloys was studies. The apparatus employed was a Nippon-Jarrell Ash AA-1 type with water-cooled fish tail burner (0.5×50 mm) and grating blazed at 3000 A.The samples (0.1 g) were dissolved in H2SO4, HF and HNO3 and then the solution was evaporated until it fumes. The solution were diluted to a determined volume according to elements and / or their contents. The flame used is either air-C2H2 for Co, Cu, Fe, Mn and Ni or N2O-C2H2 for Al, Cr, Mo, Sn and V.The absorptions measured were refered to the rectilinar calibration curves. The coefficient of variation ranges from 0.4 to 2.8%. The method is comparable in accuracy to the conventional wet chemical analysis, but faster.