Dr Mark J. Whiting

Reader in Metallic Materials, Director of the Centre for Engineering Materials


Affiliations and memberships

Chairman, Secretary and Member
Royal Microscopical Society (2001 - 2014)
Materials Section Committee
BSI (2007 - 2010)
Electron Microscopy Standards Committee
Institute of Materials (1998 - 2007)
Structure of Materials Committee


Research interests

Research collaborations

My teaching

My publications


P Yates, Christopher Mallinson, P Mallinson, Mark Whiting, Julie Yeomans (2017)An Investigation into the Nature of the Oxide Layer Formed on Kovar (Fe-29Ni-17Co) Wires Following Oxidation in Air at 700 °C and 800 °C, In: Oxidation of Metals: an international journal of the science of gas-solid reactions88(5-6)pp. 733-747 Springer

This work provides new insight and evidence that challenges and extends the accepted view of the oxidation of Kovar (ASTM-15). Specimens of 2 mm diameter Kovar wire were oxidised in air at 700 °C or 800 °C for 10 minutes. The resulting oxide layers were analysed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, scanning transmission electron microscopy and Raman spectroscopy. Oxide layers of approximately 2 μm and 4 μm thick were formed at 700 °C and 800 °C, respectively. These were found to contain iron, cobalt and traces of nickel. The combination of analysis techniques revealed that the oxide contains Fe2O3 in addition to (Fe,Co,Ni)3O4, a spinel oxide, in contrast to the combinations of Fe3O4, Fe2O3 and FeO that are typically reported. The oxide layer was found to be complex, consisting of multiple layers with different compositions which is overlooked in the existing literature.

MARK JOHN WHITING, E Williamson, Mark Gee, Daniel Robertson, JOHN FARNHAM WATTS, Mark W. Whiting, JULIE ANNE YEOMANS (2022)A comparative study of the wear performance of hard coatings for nuclear applications, In: Wear488-489204124 Elsevier B.V

Hard chromium plate (HCP) has been the wear resistant coating of choice in the nuclear industry for decades, but new protective coatings are required as a result of the hazardous nature of Cr(VI) compounds used in electroplating. This study compares the wear performance of candidate replacements materials, Cr2O3 and Cr3C2–NiCr. These two coatings are also compared with HCP and a WC-(W,Cr)2C–Ni coating assessed in an earlier publication. The Cr2O3 and Cr3C2–NiCr coatings were supplied having been applied to Inconel 625 substrates using high velocity oxy fuel (HVOF) and thermal detonation gun spray techniques, respectively. A ball-on-flat sliding wear configuration was used with three environments: dry, deionised water, and borated water to partially simulate nuclear reactor water chemistry. Wear rates were measured using both volume and mass standard metrics. The wear surface samples were characterised using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) in order to establish the operative wear mechanisms. All three candidate coating materials exhibited similar wear performance to HCP in the three test environments. There was, however, enough of a difference between performance in deionised and borated water, to merit the use of borated water in future testing. The data gathered using SEM and XPS provided insight into the wear mechanisms. These include both particle pull-out and tribolayer formation. The XPS data revealed that Cr3C2 is preferentially removed from the Cr3C2–NiCr coating during wear testing in a borated water environment. •Three ceramic and cermet coatings wear tested in reactor coolant water.•Cr2O3 is the best hard chromium plate alternative in the wear system investigated.•Deionised water is not a suitable analogue for borated water during wear testing.•Wear mechanisms include tribolayer formation and particle/material pull-out.•XPS can elucidate further information on tribolayer formation and wear mechanisms.

Sufyan Akram, Anatolii Babutskyi, A Chrysanthou, Diogo Montalvão, MARK JOHN WHITING, Om Prakash Modi (2021)Improvement of the wear resistance of EN8 steel by application of alternating magnetic field treatment, In: Wear484-485 Elsevier B.V

In the present paper, the tribological properties of untreated and magnetically treated EN8 medium-carbon steel were studied. Tribological tests were performed using a pin-on-disc friction and wear tester. The alternating magnetic field treatment has led to a reduction in the coefficient of friction by 18% and of the wear rate by 41% and to decreases in the surface roughness and the wear scar width by 30% and 12% respectively. Examination by means of transmission electron microscopy attributed these results to increased dislocation mobility and migration to the surface as a result of alternating magnetic field treatment leading to an increase in the Vickers microhardness and to an increase in compressive residual stresses at the surface. •The application of an alternating magnetic field led to improved wear resistance of EN8 steel.•TEM showed increased dislocation mobility resulting in higher compressive residual stresses and in increase in hardness.•Mechanisms leading to the increased dislocation mobility and to the improved WR are proposed and discussed.

Sufyan Akram, Anatolii Babutskyi, A Chrysanthou, Diogo Montalvão, MARK JOHN WHITING, Nada Pizurova (2021)Improvement of the wear resistance of nickel-aluminium bronze and 2014-T6 aluminium alloy by application of alternating magnetic field treatment, In: Wear480-481 Elsevier B.V

The present work has used an alternating magnetic field treatment at ambient temperature to improve the wear resistance of nickel-aluminium bronze and aluminium alloy 2014-T6. Pin-on-disc wear tests under lubricating conditions using a AISI52100 steel ball bearing as the counter face material have shown reduction in the width and depth of wear scars as well as lower values of the coefficient of friction following the treatment. The improved wear properties have been attributed to increased precipitation of κIV in the case of the nickel-aluminium bronze and of GP zones as well as θ’’ for AA2014-T6. Transmission electron microscopy also revealed changes in the dislocation distribution, while X-ray diffraction showed changes in the residual stress for both alloys. The mechanism leading to these changes is discussed by consideration of the soft ferromagnetic properties of the nickel-aluminium bronze and the paramagnetic nature of AA2014. •Improvement of the wear resistance of nickel-aluminium bronze and AA2014-T6 by application of magnetic field was recorded.•Increased dislocation mobility and precipitation were recorded, leading to redistribution of RS and increase in hardness.•Mechanisms responsible for the increased dislocation mobility and precipitation leading to the improvement were suggested.

A Arvanitis, S Diplas, P Tsakiropoulos, JF Watts, MJ Whiting, SA Morton, JAD Matthew (2001)An experimental study of bonding and crystal structure modifications in MoSi2 and MoSi2+xAl (x=10 to 40 at% Al) via Auger parameter shifts and charge transfer calculations, In: ACTA MATERIALIA49(6)pp. 1063-1078 PERGAMON-ELSEVIER SCIENCE LTD
ANDREW LEWIS MARSHALL, J. Holzer, P. Stejskal, C. J. Stephens, T. Vystavěl, MARK JOHN WHITING (2021)The EBSD spatial resolution of a Timepix-based detector in a tilt-free geometry, In: Ultramicroscopy113294 Elsevier B.V

Performing EBSD with a horizontal sample and a parallel EBSD detector sensor, enables safer specimen movements for data collection of large specimen areas and improves the longitudinal spatial resolution. The collection of electron backscattering patterns (EBSPs) at normal incidence to the electron beam has been revisited via the use of a direct electron detection (DED) sensor. In this article we present a fully operational DED EBSD detection system in this geometry, referred to as the tilt-free geometry. A well-defined Σ=3[101]{121} twin boundary in a Molybdenum bicrystal was used to measure the physical spatial resolution of the EBSD detector in this tilt-free geometry. In this study, two separate methods for estimating the spatial resolution of EBSD, one based on a pattern quality metric and the other on a normalised cross correlation coefficient were used. The spatial resolution was determined at accelerating voltages of 8 kV, 10 kV, 12 kV, 15 kV and 20 kV ranging from ∼22−38 nm using the pattern quality method and ∼31−46 nm using the normalised cross correlation method.

Vasileios Katranidis, Sai Gu, David Cox, Mark J Whiting, Spyros Kamnis (2018)FIB-SEM Sectioning Study of Decarburization Products in the Microstructure of HVOF-Sprayed WC-Co Coatings, In: Journal of Thermal Spray Technology27(5)pp. 898-908 Springer

The thermal dissolution and decarburization of WC-based powders that occur in various spray processes are a widely studied phenomenon, and mechanisms that describe its development have been proposed. However, the exact formation mechanism of decarburization products such as metallic W is not yet established. A WC-17Co coating is sprayed intentionally at an exceedingly long spray distance to exaggerate the decarburization effects. Progressive xenon plasma ion milling of the examined surface has revealed microstructural features that would have been smeared away by conventional polishing. Serial sectioning provided insights on the three-dimensional structure of the decarburization products. Metallic W has been found to form a shell around small splats that did not deform significantly upon impact, suggesting that its crystallization occurs during the in-flight stage of the particles. W2C crystals are more prominent on WC faces that are in close proximity with splat boundaries indicating an accelerated decarburization in such sites. Porosity can be clearly categorized in imperfect intersplat contact and oxidation-generated gases via its shape.

V Gopal, MJ Whiting, JW Chew, S Mills (2013)Thermal contact conductance and its dependence on load cycling, In: INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER66pp. 444-450 PERGAMON-ELSEVIER SCIENCE LTD
E Coomber, MJ Whiting, P Tsakiropoulos (2000)Eutectoid decomposition in three Ti-Co alloys, In: A Gonis, PEA Turchi, AJ Ardell (eds.), NUCLEATION AND GROWTH PROCESSES IN MATERIALS580pp. 93-98
A Chrysanthou, RC Jenkins, MJ Whiting, P Tsakiropoulos (1996)A study of the combustion synthesis of MoSi2 and MoSi2-matrix composites, In: JOURNAL OF MATERIALS SCIENCE31(16)pp. 4221-4226 CHAPMAN HALL LTD
D Barber, S Jenkins, M Whiting, M Baker (2004)Interfacial studies of double carbonate thermionic oxide cathodes over accelerated operational life, In: IVESC2004: THE 5TH INTERNATIONAL VACUUM ELECTRON SOURCES CONFERENCE PROCEEDINGSpp. 108-109
MJ Whiting, P Tsakiropoulos (1996)Process/microstructure studies of Mo(Si,Al)(2) and Nb(Si,Al)(2) intermetallics, In: TS Srivatsan, JJ Moore (eds.), PROCESSING AND FABRICATION OF ADVANCED MATERIALS IVpp. 129-137
Mark J Whiting, P Tsakiropoulos (1995)THE LEDGE MECHANISM OF PEARLITE GROWTH, In: Scripta Metallurgica et Materialia32(12)pp. 1965-1966 Elsevier
DK Barber, SN Jenkins, MJ Whiting, MA Baker (2005)Analytical interfacial studies of double carbonate thermionic oxide cathodes over accelerated operational life, In: APPLIED SURFACE SCIENCE251(1-4)pp. 42-49
V Stolojan, MJ Whiting, MJ Goringe, MJ Kelly, SRP Silva (2003)Electron energy loss line spectral and TEM analysis of heterojunctions, In: AG Cullis, PA Midgley (eds.), MICROSCOPY OF SEMICONDUCTING MATERIALS 2003(180)pp. 41-44
MJ Whiting, P Tsakiropoulos (1995)Ledge mechanism of pearlite growth: Growth velocity of ferrous pearlite, In: MATERIALS SCIENCE AND TECHNOLOGY11(10)pp. 977-984 INST MATERIALS
N.J Sutemire, M.V Rix, R.P Durman, M.A Baker, M.J Whiting (2021)Growth Anomalies in CVD Silicon Carbide Monofilaments for Metal Matrix Composites, In: Materialia101087 Elsevier B.V

The industrial scale production of silicon carbide monofilaments by chemical vapour deposition (CVD) can be disrupted by growth anomalies that initiate filament fracture during its manufacture. The anomalies take the form of growth warts on the surface of the silicon carbide fibre. Complementary 3D imaging techniques, micro X-ray computed topography (XCT) and plasma focused ion beam scanning electron microscopy (PFIB-SEM), in combination with other materials characterisation techniques (Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) analysis) have been used to investigate the nature and cause of the anomalies. Metallic tungsten particulates with an unusual dendritic morphology attached to the tungsten core were found to be the origin of the anomalies. Further investigation of the CVD system led to the observation of process-induced W oxide particulate agglomerates accumulating at the cleaning stage inlet to the reactor. These particulates became attached to tungsten wire in the cleaning stage of the CVD reactor and were rapidly reduced to elemental tungsten prior to entering the silicon carbide deposition chamber. Silicon carbide growth on the tungsten particulates results in the development of a wart-like morphology on the fibre surface. An understanding of this mechanism enabled minor modifications to reactor conditions, which prevented W oxide particulate formation and greatly reduced the occurrence of such growth anomalies. [Display omitted]

Emma Ryan, TG Sabin, John Watts, Mark Whiting (2018)The influence of build parameters and wire batch on porosity of wire and arc additive manufactured aluminium alloy 2319, In: Journal of Materials Processing Technology262pp. 577-584 Elsevier

Porosity was measured for 21 AA2319 wire and arc additive manufacture (WAAM) panels built using different wire batches, cold metal transfer (CMT) modes, wire feed speed (WFS) and travel speed (TS). Image analysis software was used to measure the porosity across two different planes, totalling an area of 84 mm2 approximately 20 layers in height. Porosity was not strongly dependent on CMT mode, WFS and WFS to TS ratio within the ranges tested but batch-to-batch variability in feedstock wire had a significant influence on area of porosity and size distribution. Wire characterisation showed that porosity did not appear to depend on bulk composition but was influenced by surface finish. Surface finish could affect hydrogen content on the wire surface and arc stability which would affect porosity. Further investigation of the relationships between surface finish and surface hydrogen content, and surface finish and arc stability is required to understand porosity formation in aluminium WAAM components.

Mark Whiting, P Tsakiropoulos (1995)Appraisal of Recent Work on Role of Crystallography in Ferrous and Nonferrous Pearlite, In: Materials Science and Technology11(8)pp. 717-727 INST Materials
MJ Whiting, V Stolojan, A Rattana, JF Watts (2003)Direct observation and characterisation of the oxide nanostructured interface resulting from organosilane pre-treatment of aluminium, In: E Manias, GG Malliaras (eds.), POLYMER/METAL INTERFACES AND DEFECT MEDIATED PHENOMENA IN ORDERED POLYMERS734pp. 27-32
MJ Whiting, MT Staff, JA Fernie, PM Mallinson, JA Yeomans (2016)Fabrication of a Glass-Ceramic-to-Metal Seal between Ti-6Al-4V and a Strontium Boroaluminate Glass, In: International Journal of Applied Ceramic Technology: ceramic product development and commercialization13(5)pp. 956-965 Wiley

Glass-ceramics are widely utilized in the electronics industry to provide electrical insulation and to form leak tight joints with a range of metals. The coefficient of thermal expansion (CTE) of the glass-ceramic can be controlled by the extent of crystallization to reduce detrimental tensile stresses in the joint. In recent years there has been interest in using titanium alloys, in place of stainless steels, due to their lower density and superior specific strength. In this study, the heat treatment of a strontium boroaluminate glass has been tailored to create glass-ceramics with mean CTEs ranging from 5.7 ± 0.1 × 10-6 K-1 to 9.7 ± 0.1 × 10-6 K-1 over the temperature range 303 K to 693 K. The resultant glass-ceramic consists of three crystalline phases and residual glass. A glass-ceramic with a mean CTE of 6.9 ± 0.1 × 10-6 K-1 was subsequently fabricated to form a compression seal with a Ti-6Al-4V housing and a pre-oxidized Kovar pin. Single pin assemblies were shown to be reproducible in terms of microstructure and all passed a standard helium leak test, indicating that a successful seal had been produced.

DK Barber, SN Jenkins, MJ Whiting, MA Baker (2004)Investigation of the nickel/emissive oxide interface in thermionic emitters, In: SURFACE AND INTERFACE ANALYSIS36(8)pp. 1190-1194
MJ Whiting (2000)A reappraisal of kinetic data for the growth of pearlite in high purity Fe-C eutectoid alloys, In: SCRIPTA MATERIALIA43(11)pp. 969-975 PERGAMON-ELSEVIER SCIENCE LTD
MJ Whiting, SL Ogin (1997)Dislocation wall structures near a stress concentration in fatigued copper polycrystals, In: SCRIPTA MATERIALIA36(7)pp. 763-768 PERGAMON-ELSEVIER SCIENCE LTD
Simon Parker, Mark Whiting, Julie Yeomans (2017)Control of carbon content in WC-Co hardmetal by heat treatment in reducing atmospheres containing methane., In: International Journal of Refractory Metals and Hard Materials66pp. 204-210 Elsevier

Pressed WC-Co hardmetal compacts of two different compositions, 6 and 10 wt.% Co, were heat treated under flowing atmospheres of nitrogen, hydrogen and methane at temperatures from 500 to 900 °C prior to sintering under argon. Microstructural examination showed excessive carburisation up to 2.5 mm into the compacts with regions most exposed to heat treatment atmospheres showing greatest carburisation. η-phase was present in the 6 wt.% Co samples heat treated at low temperatures without methane but was not present with heat treatment temperatures of 700 °C or above with methane present. The hardness of both materials was significantly lower in highly carburised regions, highlighting the need for careful control of heat treatment parameters.

Michael Rix, Mark Baker, Mark Whiting, Ray P Durman, Robert A Shatwell (2017)An Improved Silicon Carbide Monofilament for the Reinforcement of Metal Matrix Composites, In: M Meyers, HAC Benavides, SP Brühl, HA Colorado, E Dalgaard, CN Elias, RB Figueiredo, O Garcia-Rincon, M Kawasaki, TG Langdon, RV Mangalaraja, MCG Marroquin, A da Cunha Rocha, JM Schoenung, A Costa e Silva, M Wells, W Yang (eds.), Proceedings of the 3rd Pan American Materials Congresspp. 317-324 Springer

As part of ongoing research in the UK, TISICS have developed an improved 140 µm carbon coated silicon carbide monofilament for the reinforcement of metal matrix composites. The monofilament is fabricated in a single reactor using a high speed chemical vapor deposition process at a rate of 8 m/min (26 ft/min). Statistical analysis of monofilament properties over two years of production has demonstrated excellent reproducibility of the process. The monofilaments have an average tensile strength of 4.0 ± 0.2 GPa with a Weibull modulus of 50 ± 10. Composites incorporating the monofilaments show similar low variability in yield and tensile strength with the latter exhibiting a mean value above 90% of the maximum theoretical strength predicted by the rule of mixtures. By varying the volume fraction and orientation of the monofilament reinforcement, composite properties can be tailored to fit design requirements. Examples are given of demonstrator components made for the European aerospace sector.

AD Yeadon, SJ Wakeham, HL Brown, MJ Thwaites, MJ Whiting, MA Baker (2011)Remote plasma sputtering of indium tin oxide thin films for large area flexible electronics, In: Thin Solid Films520(4)pp. 1207-1211 Elsevier

Indium tin oxide (ITO) thin films with a specific resistivity of 3.5 × 10− 4 Ω cm and average visible light transmission (VLT) of 90% have been reactively sputtered onto A4 Polyethylene terephthalate (PET), glass and silicon substrates using a remote plasma sputtering system. This system offers independent control of the plasma density and the target power enabling the effect of the plasma on ITO properties to be studied. Characterization of ITO on glass and silicon has shown that increasing the plasma density gives rise to a decrease in the specific resistivity and an increase in the optical band gap of the ITO films. Samples deposited at plasma powers of 1.5 kW, 2.0 kW and 2.5 kW and optimized oxygen flow rates exhibited specific resistivity values of 3.8 × 10− 4 Ω cm, 3.7 × 10− 4 Ω cm and 3.5 × 10− 4 Ω cm and optical gaps of 3.48 eV, 3.51 eV and 3.78 eV respectively. The increase in plasma density also influenced the crystalline texture and the VLT increased from 70 to 95%, indicating that more oxygen is being incorporated into the growing film. It has been shown that the remote plasma sputter technique can be used in an in-line process to produce uniform ITO coatings on PET with specific resistivities of between 3.5 × 10− 4 and 4.5 × 10− 4 Ω cm and optical transmission of greater than 85% over substrate widths of up to 30 cm.

MJ Whiting, P Tsakiropoulos (1997)Morphological evolution of lamellar structures: The Cu-Al eutectoid, In: ACTA MATERIALIA45(5)pp. 2027-2042 PERGAMON-ELSEVIER SCIENCE LTD
RE Waters, Mark Whiting, Vlad Stolojan (2013)Examining the Pearlite Growth Interface in a Fe-C-Mn Alloy, In: International Journal of Materials and Metallurgical Engineering7(7)pp. 506-509 World Academy of Science, Engineering and Technology

A method of collecting composition data and examining structural features of pearlite lamellae and the parent austenite at the growth interface in a 13wt. % manganese steel has been demonstrated with the use of Scanning Transmission Electron Microscopy (STEM). The combination of composition data and the structural features observed at the growth interface show that available theories of pearlite growth cannot explain all the observations.

Edward H. Williamson, Mark Gee, Daniel Robertson, John F. Watts, Mark J. Whiting, Julie A. Yeomans (2019)Wear performance and characterisation of coatings for nuclear applications: WC-(W,Cr)2C-Ni and hard chromium plate, In: Wear430pp. 169-182 Elsevier

The nuclear industry has used hard chromium plate for many years but is seeking alternatives, due to the adverse health effects of Cr(VI) employed in electroplating. In this study, testing and analysis regimes for the comparison of the sliding wear performance of candidate materials have been established and the performance of WC-(W,Cr)2C-Ni has been compared with that of hard chromium plate. WC-(W,Cr)2C-Ni was applied to Inconel 625 substrates using a detonation gun thermal spray technique. Sliding wear testing was performed using a ball-on-flat configuration reciprocating tribometer at 20 °C in three environments: dry, deionised water and simulated nuclear reactor water chemistry. Wear rates have been evaluated, using both mass and volume loss, and the worn samples were analysed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The WC-(W,Cr)2C-Ni coating had a broadly comparable wear performance to hard chromium plate in all three environments. There were differences between deionised and borated water, such that the latter needs to be used in further evaluation. SEM and XPS analyses enabled the wear mechanisms for WC-(W,Cr)2C-Ni and HCP to be elucidated, including pull-out and tribolayer formation. XPS has shown that the tribolayer on WC-(W,Cr)2C-Ni is stratified and undergoes chemical changes as a result of wear.

Mark Whiting (2017)Is it a Ceramic? Is it Graphene? No it's Vibranium!, In: M Lorch, A Miah (eds.), The Secret Science of Superheroespp. 93-110 RSC Publishing
Damaso De Bono, T London, Mark Baker, Mark Whiting (2017)A robust inverse analysis method to estimate the local tensile properties of heterogeneous materials from nano-indentation data, In: International Journal of Mechanical Sciences123pp. 162-176 Elsevier

Most current analysis of nano-indentation test data assumes the sample to behave as an isotropic, homogeneous body. In practice, engineering materials such as structural steels, titanium alloys and high strength aluminium alloys are multi-phase metals with microstructural length scales that can be the same order of magnitude as the maximum achievable nano-indentation depth. This heterogeneity results in considerable scatter in the indentation load-displacement traces and complicates inverse analysis of this data. To address this problem, an improved and optimised inverse analysis procedure to estimate bulk tensile properties of heterogeneous materials using a new ‘multi-objective’ function has been developed which considers nano-indentation data obtained from several indentation sites. The technique was applied to S355 structural steel bulk samples as well as an autogenously electron beam welded sample where there is a local variation of material properties. Using the new inverse analysis approach on the S355 bulk material resulted in an error within 3% of the experimental yield strength and strain hardening exponent data, which compares to an approximate 9% error in the yield strength and an 8% error in the strain hardening exponent using a more conventional approach to the inverse analysis method. Applying the new method to indentation data from different regions of an S355 steel weld and using this data as an input into an FE model of the cross-weld, tensile data from the FE model resulted matching the experimentally measured properties to within 5%, confirming the efficacy of the new inverse analysis approach.