Enrique Alabort

• Doctor of Philosophy
• Alloyed Ltd

Introduction: Titanium-based implants can be used to fill voids in bone reconstruction surgery. Through additive manufacturing (AM), it is possible to produce titanium implants with osteoconductive properties such as high porosity and low stiffness. AM facilitates a level of design flexibility and personalization that is not feasible with tradition...

Additive manufacturing (AM) allows for the fabrication of custom orthopaedic implant devices which have complex geometries and similar mechanical properties to bone. This paper reviews the corrosion, fatigue and wear properties of AM Ti alloys to confirm their safety for use in orthopaedic implants. Specifically, AM Ti lattice geometries are highli...

Data-enabled approaches that complement experimental testing offer new capabilities to investigate the interplay between chemical, physical and mechanical attributes of alloys and elucidate their effect on biological behaviours. Reported here, instead of physical causation, statistical correlations were used to study the factors responsible for the...

Additive ManufacturingAdditive Manufacturing technologies, such as Laser Powder Bed Fusion, have enabled the creation of complex geometrical designs which can be used for lightweighting purposes across multiple industries. One of the most common methods to reduce weight in the design stage is the use of topological optimization or lattice structure...

The performance of many metal biomedical implants – such as fusion cages for spines – is inherently limited by the mismatch of mechanical properties between the metal and the biological bone tissue it promotes. Here, an alloy design approach is used to isolate titanium alloy compositions for biocompatibility which exhibit a modulus of elasticity lo...

The cover illustrates the difficulty in predicting properties in selective laser melted metals. The presence of "satellite particles", inherent to the manufacturing process, creates discrepancies between the CAD model and the as‐manufactured scaffold, manifested in a departure of actual properties from those predicted. When these structures are use...

This systematic comparison between sheet‐based triply periodic minimal surfaces (TPMS) and strut‐based ordered and disordered lattice topologies offers insights into parametric designs for tissue engineering scaffolds intended as implants. The study explores the effect of topology on compressive properties and in vitro osteoblastogenesis. TPMS‐shee...

Numerical design of TiNbTaZrMoSn alloy preceded its manufacture and mechanical, physico-chemical and in vitro characterisation. The specifications of the alloy required a multi-objective optimisation including lower modulus of elasticity than c.p.Ti, high strength, stabilised β crystal structure with a low martensitic start temperature, a narrow so...

3D printed metamaterials are a human-designed class of material capable of providing uncommon properties unseen in nature. However the freedom power of design provided by additive manufacturing in metamaterials is useless if reliable and efficient modelling design tools are not available. The objective of this work is to evaluate, validate and stud...

The mechanical properties of new low-modulus beta titanium alloyed designed for biomedical applications are measured and compared when processed via the selective laser melting (SLM) and the metal injection moulding (MIM) processes. Mechanical tensile testing reveals important differences between them: (i) Under optimal laser settings, SLM produces...

Ring-rolling has proven notoriouslyAdziman, Fauzan difficult to model, control, andTakai, Ryosuke optimise accurately. We have studied a multi-objective optimisation for the manufacturability of aero-engine turbine disc by integrating (1) geometrical constraint, (2) alloy design, and (3) process parameters. AccurateTang, Yuanbo T. computational mod...

The increasing use of orthopaedic total hip replacement implants has led to a consequent rise in the incidence of associated periprosthetic fractures (PPF). Analysis of the national joint registry data showed the choice of cemented hip stem influenced the risk of a PPF occurring. However, the effect of implant design in relation to the risk of PPF...

The rate-dependent failure response of multi-material adhesive joints for three deformation modes is investigated. A combination of carbon fibre reinforced polymers (CFRP) and titanium alloy Ti-6Al-4V is employed. The experiments provide important information about the failure sequence of a multi-material adhesive joints, which depends upon the loa...

Most existing Implants are inherently limited by the mismatch between the performance of metals and biological bone tissues. Moreover, most common Biomedical alloys raise toxicological concerns. In this paper, Alloy design is used to find optimal metallic Titanium compositions which are bio-compatible and which offer inherent lower modulus of elast...

A broad range of synthetic trabecular-like metallic lattices is 3D printed in Ti-6Al-4V by SLM. The aim is to propose new conceptual types of implant structures for superior biomechanical matching and osseo-integration: synthetic bone. Systematic evaluation is then carried out: (i) their accuracy is characterised using HR X-ray tomography, to asses...

Additive manufacturing of metals has opened a whole new range of complex functional geometries inaccessible by convectional production methods which are called to revolutionise several sectors (i.e., Biomedical, aerospace, energy). These parts usually include a wide variety of characteristic elemental length scales from thin walls/struts to bulk re...

Fracture mechanics experiments are used to investigate the rate-dependent failure of adhesively bonded structures under different deformation modes: I, II and I/II. First, the high-rate mechanical response of the adhesive interface is analysed with a newly developed method – which relies entirely upon digital image correlation. The method was purpo...

In this work, the influence of the specimen size and orientation on the strength and ductility of additive manufactured Ti-6Al-4V is analysed and rationalised in a complete framework. First, the mechanical properties are addressed – as a function of surface-type, orientation, and size. Our results show systematic strengthening and a drastic drop in...

A broad range of synthetic trabecular-like metallic lattices are 3D printed, to study the extra design free-dom conferred by this new manufacturing process. The aim is to propose new conceptual types of implant structures for superior bio-mechanical matching and osseo-integration: synthetic bone. The target designs are 3D printed in Ti-6Al-4V alloy...

An alloy design approach for titanium alloys is presented. New alloys are isolated, manufactured and tested with an emphasis on the superplastic response. The superplastic effect is found to be optimal between 650 to 750∘C at strain rates between 8.3×10⁻² and 8.3×10⁻³/s – this is a substantial improvement in terms of temperature and deformation rat...

Additive manufacturing of metals has open a whole new range of complex functional geometries inaccessible by convectional production methods which are called to revolutionise several sectors (i.e., biomedical, aerospace, energy). These parts usually include a wide variety of characteristic elemental length scales from thin walls/struts to bulk regi...

A new method for characterising the rate-dependent failure of ductile adhesively bonded structures has been developed and used to investigate the different modes of loading of representative interfaces. Furthermore, experimental observations enabled a newly developed cohesive zone model that captures all critical aspects of the observed and quantif...

Additive manufacturing is used to produce open-cell scaffolds with tailored design to match bone performance. We used triply periodic minimal surfaces within a range of sizes and volume fractions designed to suit the needs of the different existing bone tissues – this meant manufacturing sub-millimetre unit cells with pore sizes between 200 and 500...

A novel approach to accelerate greatly and simplify the determination of creep properties in metals ispresented. The method combines advanced digital image correlation, thermal imaging, and conductivegraded heating to produce and analyse viscoplastic deformation in a continuous range of temperaturesat constant stresses. By differentiating the strai...

Continuum models and miniaturised experiments are used to elucidate the high-temperature forgeability of the Ni-based superalloy Inconel 903. Uniaxial com-pression high temperature tests allow the derivation of an apparent activationenergy and the strain rate sensitivity of the deformation process, and to proposea unified constitutive model that ca...

Adhesively bonded joints subjected to dynamic loading demand reliable and accurate measurement techniques to capture their rate dependent traction–separation behaviour. Particularly challenging is the measurement of damage and failure processes which are fundamental to develop the corresponding cohesive zone models. This paper proposes a new experi...

A titanium-based alloy composition consisting, in weight percent, of: between 0.5 and 2.5% aluminium, between 0.5 and 1.5% vanadium, between 0.0 and 3.0% iron, between 0.0 and 1.0% chromium, between 0.0 and 3.0% nickel, between 1.0 and 4.0% molybdenum, between 0.0 and 1.0% silicon, between 0.0 and 0.2% boron, between 0.0 and 0.5% tin, between 0.0 a...

Surface observations are used to elucidate the deformation mechanisms responsible forsuperplasticity in the Ti-6Al-4V and Ti-4Al-2.5V-1.5Fe titanium alloys. First, stress relaxation testsare used to quantify the difference in superplastic behaviour of each alloy. Then, high-temperature insitutensile tests are performed in the scanning electron micr...

The design, operation, and performance of a laboratory-scale X-ray computed tomography arrangement that is capable of elevated-temperature deformation studies of superalloys to 800 °C and possibly beyond are reported. The system is optimized for acquisition of three-dimensional (3D) backprojection images recorded sequentially during tensile deforma...

An electro-thermal mechanical testing (ETMT) system is used to assess the mechanical behavior of a prototype single-crystal superalloy suitable for industrial gas turbine applications. Miniaturized testpieces of a few mm² cross section are used, allowing relatively small volumes to be tested. Novel methods involving temperature ramping and stress r...

Miniaturised tensile tests coupled with in-situ scanning electron microscopy are used to deduce the grain boundary properties of a nickel-based superalloy at 750 °C. This allows the damage initiation, evolution and failure processes to be observed directly. The significant variation in ductility – consistent with the limited number of grain boundar...

An elasto-viscoplastic thermodynamically consistent constitutive model for diffusion-assisted phase transformations is presented here. The model accounts for the different deformation mechanisms, their time dependence, the crystal rotations produced by microtwin propagation and the chemistry-plasticity coupling occurring at high temperature. It is...

The increasing use of adhesive joints in dynamic applications require reliable measurements of the rate-dependent stress-displacement behaviour. The direct measurement of the stress-displacement curve is necessary when using cohesive models in discretised solutions of boundary value problems in solid mechanics. This paper aims to investigate the ra...

2017 Acta Materialia Inc. The contribution of a microtwinning mechanism to the creep deformation behaviour of single crystal superalloy MD2 is studied. Microtwinning is prevalent for uniaxial loading along 〈011〉 at 800°C for the stress range 625 to 675 MPa and 825°C for 625 MPa. Using quantitative stereology, the twin fraction and twin thickness ar...

The contribution of a microtwinning mechanism to the creep deformation behaviour of single crystal superalloy MD2 is studied. Microtwinning is prevalent for uniaxial loading along at C for the stress range 625 to MPa and C for 625 MPa. Using quantitative stereology, the twin fraction and twin thickness are estimated; this allows the accumulated cre...

The role of boron in promoting ductility at high temperature in a prototype nickel-based superalloy designed for industrial gas turbines is studied. Both a boron-containing and boron-free variant are tested in tension at 750 °C, with further in-situ tests carried out using scanning electron microscopy (SEM), to clarify the mechanism of ductility im...

An in-situ testing method for high-temperature time-resolved surface observations inside the scanning electron microscope is described and used to improve the mechanistic understanding of a new polycrystalline nickel-based superalloy. The in-situ observations are able to elucidate surface mechanisms of damage in different deformation regimes. Tensi...

Surface observations are used to elucidate the deformation mechanisms responsible for the superplastic effect in Ti–6Al–4V. High-temperature in-situ tests for tensile and shear deformation modes are performed in the scanning electron microscope at temperatures in excess of 700∘ C. Grain boundary sliding is predominant; the micro-mechanics of accomm...

Phase transformations in prototype high strength polycrystalline nickel-based superalloys of varying Ti/Nb ratio are studied using time-resolved, high resolution X-ray synchrotron diffractometry. The dissolution kinetics of the ordered phase Ni 3 (Al, Ti, Nb, Ta) upon heating to the solutioning temperature of $1200 °C and its reprecipitation on coo...

Abstract The processing regime relevant to superplasticity in the Ti-6Al-4V alloy is identified. The effect is found to be potent in the range 850-900°C at strain rates between 0.001/s and 0.0001/s. Within this regime, mechanical behaviour is characterised by steady-state grain size and negligible cavity formation; electron backscatter diffraction...