Dr Mark J. Whiting


Senior Lecturer in Metallic Materials, Director of the MSc in Advanced Materials
BEng(Hons) MA PhD CEng MIMechE FIMMM FRMS

Biography

Affiliations and memberships

Variously
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

Research interests

Research collaborations

My teaching

My publications

Publications

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
Mark Whiting, P TSAKIROPOULOS (1994)THE LEDGE MECHANISM OF PEARLITE GROWTH - SOME THOUGHTS ON THE SOLUTION TO THE KINETIC PROBLEM, In: SCRIPTA METALLURGICA ET MATERIALIA30(8)pp. 1031-1036 PERGAMON-ELSEVIER SCIENCE 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
V Gopal, MJ Whiting, JW Chew, S Mills (2012)FINITE ELEMENT ANALYSIS AS A TOOL FOR CALCULATING THE THERMAL CONTACT CONDUCTANCE FOR A MACHINED SURFACE, In: PROCEEDINGS OF THE ASME SUMMER HEAT TRANSFER CONFERENCE, 2012, VOL 1pp. 643-650
Mark J Whiting, P Tsakiropoulos (1995)THE LEDGE MECHANISM OF PEARLITE GROWTH, In: Scripta Metallurgica et Materialia32(12)pp. 1965-1966 Elsevier
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: POLYMER/METAL INTERFACES AND DEFECT MEDIATED PHENOMENA IN ORDERED POLYMERS734pp. 27-32
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.

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
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.

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.

Mark Whiting, P TSAKIROPOULOS (1993)ON THE LEDGE MECHANISM OF PEARLITE GROWTH - THE CU-AL LAMELLAR EUTECTOID, In: SCRIPTA METALLURGICA ET MATERIALIA29(3)pp. 401-406 PERGAMON-ELSEVIER SCIENCE LTD
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]

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
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.

E Coomber, MJ Whiting, P Tsakiropoulos (2000)Eutectoid decomposition in three Ti-Co alloys, In: NUCLEATION AND GROWTH PROCESSES IN MATERIALS580pp. 93-98
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
V Stolojan, MJ Whiting, MJ Goringe, MJ Kelly, SRP Silva (2003)Electron energy loss line spectral and TEM analysis of heterojunctions, In: MICROSCOPY OF SEMICONDUCTING MATERIALS 2003(180)pp. 41-44
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.

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.

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
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.

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
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
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.

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
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: 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.

Mark Whiting (2017)Is it a Ceramic? Is it Graphene? No it's Vibranium!, In: The Secret Science of Superheroespp. 93-110 RSC Publishing
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
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.

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.

MJ Whiting, P Tsakiropoulos (1996)Process/microstructure studies of Mo(Si,Al)(2) and Nb(Si,Al)(2) intermetallics, In: PROCESSING AND FABRICATION OF ADVANCED MATERIALS IVpp. 129-137
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