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Titanium-tantalum alloys have historically been difficult to produce using conventional techniques due to the large difference in melting point and poor interdiffusivity rates of the two elements, leading to large levels of segregation. In this work we have investigated using the Metalysis-FFC process to overcome this problem. The Metalysis-FFC process is an electrochemical process where metal oxides are reduced by acting as a cathode in an electrolytic cell combined typically with a graphite anode and molten calcium chloride electrolyte. Previous work has proven that the process works when applied to mixed oxides to produce alloys. The reduction process is performed in the solid state and so negates the problems associated with traditional melting practices such as segregation and evaporation losses. In this work we have been able to successfully produce a range of Ti-Ta alloy powders from pure titanium to pure tantalum in 10 wt% increments using the Metalysis-FFC process. Moreover, energy dispersive spectroscopy analysis of the powders suggests uniform distribution of titanium and tantalum within all compositional ranges, suggesting the Metalysis-FFC process has the potential to be a transformative manufacturing methodology for producing titanium-tantalum alloys.

ConformTM is an extrusion process, which has been in use since the 1970s. Although it is primarily used with aluminium or copper rod/powder feedstocks, work at the Univ. Sheffield over the last decade has involved the use of titanium feedstocks for various applications. This paper expands on this knowledge by utilising low cost, aerospace titanium alloy swarf, which is the largest waste product from the manufacturing of aerospace titanium components. Swarf is fed into a ConformTM extrusion machine at room temperature and is fully consolidated into round wire/rod profiles in one, solid-state step, using modified tooling for titanium. Such wire can be used for additive manufacture or welding wire. To date there has been numerous successful trials in this challenging process, including the production of both 10 mm commercially pure titanium rod (from powder) and, more importantly, the production of 5 mm diameter Ti-6Al-4V wire from swarf. The material produced has since been characterised using light and electron microscopy and mechanical properties determined using tensile testing and microhardness indenting.

Non-standard processing routes for the manufacture of industrial scale Ti834 billet have been undertaken to investigate their effect on macrozones in final forged product. Microstructure, texture and dwell fatigue fracture surfaces were characterised from forged disc samples fabricated from these new billets. All processing routes showed a bimodal microstructure consisting of 25pct of primary alpha grains in a transformed beta matrix. Texture analysis has revealed variations in the presence and size of macrozones with relatively weak textures. Quasi-cleavage facets were present in all dwell fatigue samples although the fatigue life was doubled for the sample whose thermomechanical processing has the highest imposed strain.

Titanium alloys are used extensively in the aerospace sector due to the good combination of high strength-to-weight ratio and corrosive resistance. Many aerospace components are exposed to extreme service stress states and temperatures, which in some applications could compromise the component’s performance if a single titanium alloy is used. A potential solution to this issue could be the combination of dissimilar titanium alloys in subcomponent regions, achieved through consolidating powders via field assisted sintering technology (FAST-DB) and subsequent hot forging (FAST-forge). In this paper, near net shape titanium-titanium alloy demonstrator components are produced from oversized AM powders in just two hybrid solid-state steps; FAST-DB and hot forging.

Field assisted sintering technology (FAST), also known as spark plasma sintering (SPS), is increasingly utilised to process powders/particulates of engineering alloys and metal-based composite materials. FAST is currently extensively used at laboratory scale by research institutes and universities as a rapid and cost‑effective process to consolidate powders. This includes investigating new alloy compositions and material combinations, improving established materials’ properties, and consolidating materials considered challenging/impossible through conventional sintering techniques. FAST is gaining traction for industrial applications with possible benefits as an alternative to hot isostatic pressing or conventional melt-wrought processing. FAST preform complexity is improving and near-net-shape components are becoming a possibility. Demonstrator components for the aerospace and automotive sectors, including aeroengine blades, brake callipers and rocker arms, have been produced from titanium alloy powders. FAST has also been demonstrated as an effective intermediate step for consolidating a range of feedstocks, including recycled materials, into shaped billets that can be further processed to refine shape and/or properties. Hybrid processes such as FAST‑forge and FAST‑DB have been developed that can produce affordable titanium components with forged properties. This paper presents the current status, emerging developments, and challenges of FAST for titanium-based powders and particulates.

To increase the strength of titanium alloys beyond that achievable with α-β microstructures, alternative reinforcing methods are necessary. Here, field-assisted sintering technology (FAST) has been used to produce a novel Ti-5Al-5Mo-5V-3Cr (Ti-5553) metal-matrix-composite (MMC) reinforced with 0-25 wt.% of a ∼2 GPa yield strength TiFeMo alloy strengthened by ordered body-centred cubic intermetallic and ω phases. The interdiffusion region between Ti-5553 and TiFeMo particles was studied by modelling, electron microscopy, and nanoindentation to examine the effect of graded composition on mechanical properties and formation of α, intermetallic, and ω phases, which resulted in a > 200 MPa strengthening benefit over unreinforced Ti-5553.

Reducing the high cost of titanium to a level where it can compete with currently used commodity metals offers opportunities to many industries to exploit its excellent combination of properties to improve performance or reduce weight. The key to decreasing cost is to reduce the number of processing steps to go from ore to component, as well as material wastage from excessive machining. This paper describes a new solid-state hybrid manufacturing route, termed by the authors as FAST-forge, for converting titanium alloy powder into components with wrought properties in two steps; utilising field assisted sintering technology (FAST) to produce a shaped preform billet that is finished to near net shape by a one-step precision hot forge. The route has been demonstrated at the laboratory scale using Ti-6Al–4V hydride-dehydride powder by producing fully consolidated, microstructurally homogeneous, double truncated cone specimens directly through FAST, which were then upset forged at a range of temperatures and strain rates. The microstructural evolution and forging behaviour of the Ti-6Al–4V after FAST consolidation is similar to conventional melt, multi-step forged product. Break up of primary α at high strains was observed at 950°C and 0.01 s−1, 0.1 s−1, and 1 s−1. There is good agreement between finite element modelling of the hot forging and the experimental data, which will enable more complex shaped geometries to be produced via the proposed FAST-forge route in future. Such a route could be used to consolidate powder from a lower-cost alternative extraction method to become a disruptive technology that will enable a step-change in the economics of titanium components.

This study examined the neuropsychological profile, mental health outcomes, and coping strategies of chronic alcohol users involved in drug and alcohol counselling and investigated whether these factors could predict treatment outcome. The findings indicated that as compared with controls, chronic alcohol users demonstrated significant deficits in visuospatial, memory and executive functioning, and a higher level of emotional distress. At a 3-month follow-up, memory ability was found to significantly predict the percentage of goals achieved in counselling, the likelihood of dropout from therapy, and the likelihood of remaining abstinent. The value of further research into the influence of additional factors, such as executive functioning, mood, and coping strategies, on treatment outcomes in a larger sample was also supported.

Andreev reflection of quasiparticle excitations provides a sensitive and passive probe of flow in superfluid 3 He-B. It is particularly useful for studying complex flows generated by vortex rings and vortex tangles (quantum turbulence). We describe the reflection process and discuss the results of numerical simulations of Andreev reflection from vortex rings and from quantum turbulence. We present measurements of vortices generated by a vibrating grid resonator at very low temperatures. The Andreev reflection is measured using an array of vibrating wire sensors. At low grid velocities, ballistic vortex rings are produced. At higher grid velocities, the rings collide and reconnect to produce quantum turbulence. We discuss spatial correlations of the fluctuating vortex signals measured by the different sensor wires. These reveal detailed information about the formation of quantum turbulence and about the underlying vortex dynamics.

In the studies of both classical and quantum turbulence, significant attention is devoted to the investigation of the behavior of various submerged resonators. Upon entering the turbulent regime, the oscillators start to experience a significant drag force, which varies non-linearly with velocity. We present an empirical way of modeling such systems, and calculate the expected resonant response of such oscillators near the fundamental frequency as a function of the applied driving force. We apply the model to the crossover from linear to non-linear drag forces and compare with previous models as well as selected experimental data on the transition to turbulence in oscillatory flow of 4He.

In the course of studying the R 3 Pt 23 Si 11 series (R=rare earth), we have recently synthesized Nd 3 Pt 23 Si 11 . It crystallizes in a face-centered cubic structure ( Fm-3m space group) with a lattice parameter of 16.8493(4) A at room temperature. Heat capacity and magnetic measurements show the existence of a magnetic transition at 1.6 K. Measurements of the susceptibility and magnetization down to 95 mK reveal metamagnetic behavior confirming antiferromagnetic ordering. Powder neutron diffraction experiments show that the magnetic propagation vector is k =[000] and that the 6 neodymium moments in the unit cell are antiferromagnetically coupled in pairs.

This study investigated episodic and procedural memory retention in early and late pregnancy and whether memory retention was related to sleep disruption. Twenty‐six women in the third trimester of...

The 21st Annual Conference of the Sheffield Metallurgical and Engineering Association was held on the 19 and 20 June 2012 at the Endcliffe Conference Centre, University of Sheffield. The conference...

We report recent investigations into the transition to turbulence in superfluid $^4$He, realized experimentally by measuring the drag forces acting on two custom-made quartz tuning forks with fundamental resonances at 6.5 kHz and 55.5 kHz, in the temperature range 10 mK to 2.17 K. In pure superfluid in the zero temperature limit, three distinct critical velocities were observed with both tuning forks. We discuss the signicance of all critical velocities and associate the third critical velocity reported here for the first time with the development of large vortical structures in the flow, which thus starts to mimic turbulence in classical fluids. The interpretation of our results is directly linked to previous experimental work with oscillators such as tuning forks, grids and vibrating wires, focusing on the behavior of purely superfluid $^4$He at very low temperatures

We present proof-of-concept measurements of the vortex line density generated by a quartz tuning fork resonator probed by the attenuation of second sound in superfluid $$^4$$ He at 1.6 K. The force–velocity response of a quartz tuning fork operating at a frequency of 31 kHz exhibited the onset of extra damping at a velocity of 0.5 ms $$^{-1}$$ . Attenuation of the 5th resonant mode of second sound was observed at the same velocity, indicating the production of vortex lines. Our measurements demonstrate that an increase of the drag coefficient corresponds to the development of quantum turbulence.

Precision turning is an energy-intensive, yet important machining operation for critical aero-structural titanium alloy parts. High-resolution electron backscatter diffraction reveals an increase in induced subsurface deformation with increasing surface speed, contradicting observations when applying standard surface integrity techniques. Subsurface microstructural damage, such as mechanical twins and intense slip bands, provides nucleation sites for silicide precipitation during thermal exposure at 750 °C, indicating that creep and fatigue strength could be locally reduced at the machined surface.

We present measurements of the force-velocity response of a vibrating wire resonator in superfluid 3He-B at very low temperatures. At low velocities the response is dominated by intrinsic (vacuum) damping whilst at high velocities it is dominated by pair-breaking. At intermediate velocities there is a series of small plateaus where the velocity often shows small oscillations. We believe that the behaviour results from the stretching of vortices pinned to the wire. The vortices grow and self-reconnect, emitting a vortex ring. The behaviour is very sensitive to the presence of surrounding vortices generated by a neighbouring vibrating wire.

The effect of shot peening on the microstructure, oxygen ingress and high-cycle fatigue properties of a near-α titanium alloy is investigated. Microstructural characterization of shot-peened material is performed through light microscopy, scanning electron microscopy and electron backscatter diffraction. Oxygen uptake during thermal exposure is analytically determined using secondary ion mass spectrometry. Shot peening leads to an increase in subsurface oxygen content following thermal exposure in air and the increased levels of oxygen content are accompanied by the precipitation of silicides along (or in close proximity to) the mechanical twin boundaries and in regions of high dislocation density. Preliminary fatigue data obtained through a staircase loading method show that a decrease in room temperature fatigue performance occurs in shot-peened material following prolonged thermal exposure in air at 650 °C. The observed phenomena suggest that shot peening may be deleterious to the mechanical integrity of titanium alloy components that are subject to high temperature exposure in oxidizing environments.

Shot peening introduces subsurface residual compressive stresses in titanium alloys to depths of up to 500 µm. Although the microhardness method is established as a method for determining interstitial oxygen concentration gradients of such alloys, the near surface plastic deformation arising from shot peening is a source of measurement unreliability. An alternative method based on negative ion, focused ion beam–SIMS has been trialed for a shot peened Ti-834 alloy thermally exposed for times and temperatures comparable with service conditions in the ‘hot-end’ compressor stages of a modern gas-turbine aero-engine. Focused ion beam–SIMS measurements successfully measured enhanced oxygen ingress into the topmost 100 µm of the shot-peened Ti-834 after prolonged thermal exposure. Copyright © 2012 John Wiley & Sons, Ltd.

The role of workpiece temperature on plastic deformation mode during shot peening has been investigated for two titanium alloys: commercially pure titanium and a near-α alloy. The subsurface deformation microstructures have been characterized through light microscopy, microhardness and electron backscatter diffraction.

This study used an analogue design to investigate post-concussion syndrome and the psychological and psychosocial processes associated with post-concussion symptom (PCSx) reporting. The study examined the role of expectation in reporting of PCSx, the nature of associated psychological and psychosocial difficulties, and the “good-old-days” phenomenon. Forty-five healthy participants were randomly assigned to one of two groups: (1) a control group or (2) an expectation group who were asked to perform as if they had experienced a mild traumatic brain injury. Fourteen psychiatric patients comprised the clinical group. Self-report questionnaires assessing PCSx and psychological and psychosocial variables were administered. It was hypothesised that PCSx would be non-specific, that the expectation group would report greater dysfunction than controls, and that the “good-old-days” phenomenon would cause the expectation and clinical groups to underestimate pre-morbid PCSx. All participants reported some degree of dysfunction, and the expectation and clinical groups underestimated past PCSx. The expectation group reported more PCSx and psychological and psychosocial dysfunction than controls, resembling the clinical group. The results demonstrate that expectation can cause otherwise healthy individuals to resemble a clinical group in terms of their level of endorsement of psychological and psychosocial dysfunction.

The flow behaviour of Ti–5Al–5Mo–5V–3Cr with an initial microstructure containing acicular α platelets has been characterised during isothermal subtransus forging. Flow softening was observed, following yielding and limited hardening, for all investigated temperatures and strain rates, before a steady state flow regime being reached at a strain of ∼0·5. The acicular α plates were found to have been fragmented by the forging process, which is concurrent with previous findings. The flow behaviour of the fully retained β phase below the β transus temperature has been established and found to be similar to that of the steady state flow of platelet α in a β matrix. Forging the acicular α microstructure to low strains resulted in higher dislocation concentrations in the β matrix than could be observed in the α precipitates, supporting the hypothesis of hardening through dislocation impedance. Evidence of fragmentation via a pinch-off mechanism was found where slip was observed to have been transmitted a...

The 19th Annual Conference of the Sheffield Metallurgical and Engineering Association (SMEA) was held on the 22nd to 23rd June 2010 at the Endcliffe Conference Centre, University of Sheffield, The aim of the conference was to explore recent advances in the manufacturing technologies for alloy steels, nickel-based superalloys and light metals for a range of applications. Five technical sessions focused on Process Technology, Near Net Shape Manufacture, Surface Engineering, Welding & Joining and Product Innovation.

This study investigated episodic and procedural memory performance in early and late pregnancy. Twenty-six women in the third trimester of pregnancy, 20 women in the first trimester of pregnancy, and 24 nonpregnant controls were administered a battery of verbal and visual episodic memory tasks and two procedural memory tasks. Results indicated that compared to controls, both pregnant groups had reduced scores on immediate and delayed verbal episodic memory tasks, but were unimpaired on visual and procedural memory tasks. Verbal memory differences could not be accounted for by mood state or attention; however, progesterone level accounted for a small amount of the variation. Although memory differences were minor, the perception of memory problems may have implications for everyday living for pregnant women.

Background Anecdotal reports of sleep disturbance during pregnancy are abundant; however, objective measurement of sleep changes has so far produced conflicting results. Aims To objectively measure sleep architecture and investigate subjective sleep quality in the first and third trimester of pregnancy, when compared to the nonpregnant state. Methods Twenty-seven women in the third trimester of pregnancy, 21 women in the first trimester of pregnancy and 24 nonpregnant control women underwent overnight polysomnography and completed questionnaires regarding sleep quality and mood. Results Women in the third trimester of pregnancy had poorer sleep efficiency, more awakenings, less stage 4 sleep, more stage 1 sleep and fewer minutes in rapid eye movement sleep when compared to the control group. Cortical arousals were seen more often during pregnancy, particularly in response to respiratory events and limb movements. Sleep during the first trimester was affected to a lesser extent, with more wake time after sleep onset and less stage 4 sleep when compared to the controls. Conclusions Sleep during pregnancy is compromised by higher amounts of wake and cortical arousals leading to sleep fragmentation, with greater amounts of light sleep and less deep sleep. Mood state did not have an effect on sleep. Given the impact of sleep on well-being, this study increases our understanding of the characteristics of sleep during pregnancy, to help recognise when severe sleep disruption may warrant referral to a specialist for appropriate diagnosis and treatment.

We report on the onset of turbulence in normal and superfluid 4He using several 13.5 μm diameter vibrating wire resonators placed in a cell, filtered from the surrounding helium bath. We measured the force-velocity characteristics of the wires in normal and superfluid helium over a velocity range up to several meters per second. The transition from laminar to turbulent behavior can be clearly identified. Surprisingly we find that, depending on the cooling history, turbulence in the superfluid does not always develop fully.

The vibrational mode frequencies of a taut string depend on the form of its mass distribution. To lowest order, deviations away from a uniform mass density that are even about the center of the string cause shifts in the overtones away from harmonic, while deviations that are odd do not. The problem of determining the overtone series for a given mass distribution is formulated and a full solution is derived for variations in the inverse mass density that are expressed as a Fourier cosine series. Variations arising from a single Fourier component predominantly shift the relative frequency of a single mode, with the 2nth Fourier component shifting the frequency of the nth mode. For a physically reasonable range of mass density variations, the frequency of a mode can typically be shifted by two semitones. Wrapped metal strings with variations in inverse mass density with different Fourier components have been fabricated, characterized, and tested. Light plucking produces overtones in agreement with the model; ordinary plucking produces incommensurate tones at sum and difference frequencies. Overtone series with several different major and minor tones are possible for variations involving more than one Fourier component.

Multiple extrusion of Al-4Mg-1Zr (wt.%) is presented as a severe plastic deformation technique to develop an ultra-fine grained material, using rapidly solidified needles as a feedstock. After each extrusion pass the microstructure is refined, the primary Al3Zr precipitates are broken down and

Continuous extrusion (Conform™) is a well-established technique for the production of profiles from both solid and particulate feed stock. To the first approximation it is considered to be analogous to conventional extrusion, although there are significant differences in the metal flow during both processes. Metal flow during conventional extrusion is characterised by relatively low redundant work, whereas the Conform™ process requires significant redundant work to be successful. Most of the available scientific literature to date is concerned with the simulation of the Conform™ process and not its effect on the resultant microstructure of the product. In this paper, a detailed comparison of the microstructure, texture and superplastic properties developed during Conform™ and conventional extrusion for a particulate Al–4Mg–1Zr alloy are presented.

The majority of aero-structural titanium alloys are high-speed milled. This paper identifies microstructural subsurface damage in the form of intense slip bands after high-speed milling of Ti–6Al–4V and Ti-834. Such microstructural features are undetected by current surface integrity techniques. The alignment and density of the intense slip bands were found to be dependent on the subsurface alpha grain orientation. Such microstructural subsurface damage could degrade in-service properties, due to a reduction in fatigue crack initiation resistance.

While magnesium alloys are routinely used in engineering applications in the form of net shape castings, applications for sheet product have been limited due to the poor cold formability of magnesium combined with the perceived expense of sheet. The issues associated with poor cold formability could largely be overcome if magnesium alloys were to be superplastically formed. Superplasticity in magnesium is well established with research papers on the subject dating back to the late 1960s. In recent years, interest in this area has grown to the point where a number of companies have successfully superplastically formed prototype automotive panels from magnesium alloy sheet. Concurrent to this the scientific community have demonstrated superplasticity in a wide range of magnesium alloys using processing techniques ranging from the exotic (severe plastic deformation) to the mundane (traditional warm rolling). Work by the current authors has shown, rather surprisingly, that superplasticity can be achieved in magnesium alloys in the as-cast condition. This has led to some initial exploratory work involving twin roll casting. The concept being that affordable superplastic magnesium sheet could be produced via twin roll casting with only limited rolling reduction to final gauge. This paper describes the superplastic behaviour (in uniaxial tension) and microstructure of sheet processed from strip cast AZ31 and AZ91. The experimental material has included strip cast AZ91 subjected to large shear strains immediately prior to casting. The material was tested in the as-cast condition and after warm rolling to a number of gauges. Industrially useful superplastic capability was demonstrated in the strip cast alloys. Furthermore, good superplastic capability was also demonstrated in sheet subsequently rolled from the cast metal and rolling strain did not significantly influence the ductilities obtained. The mechanism for achieving superplasticity in as-cast magnesium alloys will be considered and the contrasting deformation characteristics of AZ31 and AZ91 will be discussed in terms of m value analysis and microstructural characterisation.

Friction stir welding (FSW) can dramatically reduce grain size conferring excellent superplastic properties in certain aluminium alloys. Consequently, FSW of thick plate followed by rolling to sheet could potentially be used as a method of producing wide superplastic sheet from extrusion blanks for automotive applications. An extruded Al–4Mg–1Zr alloy was FSW prior to rolling to sheet. The structure of the FSW region after rolling was complex and in certain cases significant grain coarsening resulted during heating to the superplastic deformation temperature. A detailed investigation of the factors responsible is available here.

We have measured the damping on a quartz tuning fork in the B-phase of superfluid He-3 at low temperatures, below 0.3T (c). We present extensive measurements of the velocity dependence and temperature dependence of the damping force. At the lowest temperatures the damping is dominated by intrinsic dissipation at low velocities. Above some critical velocity an extra temperature independent damping mechanism quickly dominates. At higher temperatures there is additional damping from thermal quasiparticle excitations. The thermal damping mechanism is found to be the same as that for a vibrating wire resonator; Andreev scattering of thermal quasiparticles from the superfluid back-flow leads to a very large damping force. At low velocities the thermal damping force varies linearly with velocity, but tends towards a constant at higher velocities. The thermal damping fits very well to a simple model developed for vibrating wire resonators. This is somewhat surprising, since the quasiparticle trajectories through the superfluid flow around the fork prongs are more complicated due to the relatively high frequency of motion. We also discuss the damping mechanism above the critical velocity and compare the behaviour with other vibrating structures in superfluid He-3-B and in superfluid He-4 at low temperatures. In superfluid He-4 the high velocity response is usually dominated by vortex production (quantum turbulence), however in superfluid He-3 the response may either be dominated by pair-breaking or by vortex production. In both cases the critical velocity in superfluid He-3-B is much smaller and the high velocity drag coefficient is much larger, compared to equivalent measurements in superfluid He-4.

Effective routes for the consolidation of cost affordable titanium powder are essential for the fabrication of titanium components at acceptable production costs. An in-house canning and degassing ...

The FFC Cambridge process is ideal for NiTi production, as it avoids the Ni segregation associated with pyrometallurgical routes to manufacture NiTi, and is able to produce a homogenous low-oxygen product. The process involves the direct electrodeoxidation of NiTiO3 (first stable oxide to form upon mixing and sintering of NiO and TiO2) to NiTi in a molten CaCl2 salt bath. This work builds on previous literature that has elucidated the reduction pathway by investigating the effect of reduction temperature and current collector material on the microstructure of the final reduction product. It was found that the use of a Ni current collector caused Ni-enrichment at the surface of the product, stabilizing the high temperature B2 cubic form to room temperature. Ni-rich phases Ni4Ti3 and Ni3Ti were observed after 24h reductions. The former is favoured at higher reduction temperatures, and the latter at lower temperatures. Mechanisms for formation are proposed.

High-strength metastable β alloys, for example, Ti-5Al-5Mo-5V-3Cr, have replaced steel as the material of choice for large components, such as the main truck beam on the latest generation of airframes. The production of these components is carried out by hot near-net-shape forging, during which process variable control is essential to achieve the desired microstructural condition and subsequent mechanical properties. The flow behavior and microstructural evolution during subtransus isothermal forging of Ti-5Al-5Mo-5V-3Cr has been investigated for two different starting microstructures and analysis has incorporated previously published results. The flow behavior, irrespective of initial microstructural condition, is found to be very similar at strains ≥0.35. It is thought that this is due to a common microstructural state being reached, where dynamic recovery of the β phase is the dominating deformation mechanism. At strains

β -Ti alloy Gum metals were defined as Ti–24(Nb + Ta + V)–(Zr,Hf)–O (at.%) by Saito et al. [T. Saito et al., Science 300 (2003) 464]. Previous work has focused on compositions near Ti–23Nb–0.7Ta–2Zr–O. Here, Ti–24V–28Zr–2O was examined; similar single-crystal elastic constants were observed. However, the alloy was found to be brittle and did not form α ″ during loading, unlike the Ti–Nb alloy. V-rich body-centred cubic precipitates were also observed. Therefore the β stability parameters e / a , Bo and Md alone are insufficient to define the compositional range of Gum metals.