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Rolls-Royce UTC

Department of Materials Science and Metallurgy

Studying at Cambridge

 

Dr Howard Stone

Dr Howard Stone

Assistant Director of Research

Deputy Director


Office Phone: +44 (0)1223 334320

Biography:

2006 Assistant Director of Research

2000 PhD (Cambridge)

1995 MA (Cambridge)

Research Interests

High-Temperature Materials

The ongoing drive for improved fuel efficiency and reduced emissions from gas-turbine aeroengines continues to demand new materials capable of tolerating ever higher service temperatures. At present, the majority of these applications are served by nickel-base superalloys, but new materials are now also being considered as potential successors to these alloys in many applications.

Nickel-base superalloys

The outstanding combination of properties of nickel-base superalloys has led to their widespread use in hot-section aeroengine components. By developing an improved understanding of the relationship between the alloy composition, microstructure and properties, and how these are influenced by the processing and service conditions, we are developing new alloys with superior properties than their predecessors.

Novel high-temperature materials

Novel materials that may provide viable alternatives to nickel-base superalloys in high-temperature applications such as aeroengines are also being investigated. While no material improves on conventional nickel-base superalloys in all regards, an understanding of the conditions that must be tolerated by individual components is leading to the identification and development of novel materials that may enable higher temperatures, stresses, longer lives or lighter components to be achieved.

In-situ characterization of phase transformations

Modern diffraction-based techniques using neutron (e.g. the ISIS and ILL neutron sources) and synchrotron sources (e.g. the Diamond Light Source and European Synchrotron Radiation Facility) offer powerful methods for the in-situ characterisation of crystal structures in metals and alloys. With these methods, phase transformations and deformation behaviour are being studied on timescales of milliseconds and with very high resolution, providing unique insights into these processes.

Key Publications

  1. Mignanelli, P.M., Jones, N.G., Hardy, M.C., Stone, H.J., The influence of Al: Nb ratio on the microstructure and mechanical response of quaternary Ni-Cr-Al-Nb alloys, Materials Science and Engineering A, 612, pp. 179-186 (2014).
  2. Jones, N.G., Humphrey, C., Connor, L.D., Wilhelmsson, O., Hultman, L., Stone, H.J., Giuliani, F., Clegg, W.J., On the relevance of kinking to reversible hysteresis in MAX phases, Acta Materialia, 69, pp. 149-161 (2014). 
  3. Bhowmik, A., Bennett, R.J., Monserrat, B., Conduit, G.J., Connor, L.D., Parker, J.E., Thompson, R.P., Jones, C.N., Stone, H.J., Alloys based on Cr-Cr2Ta containing Si, Intermetallics, 48, pp. 62-70 (2014).
  4. Bhowmik, A., Knowles, K.M., Stone, H.J., Discontinuous precipitation of Co 3V in a complex Co-based alloy, Philosophical Magazine, 94 (8), pp. 752-763 (2014). 
  5. Collins, D.M., Stone, H.J., A modelling approach to yield strength optimisation in a nickel-base superalloy, International Journal of Plasticity, 54, pp. 96-112 (2014).
  6. Jones, N.G., Aveson, J.W., Bhowmik, A., Conduit, B.D., Stone, H.J., On the entropic stabilisation of an Al0.5CrFeCoNiCu high entropy alloy,  Intermetallics, 54, pp. 148-153 (2014). 
  7. Connor, L.D., Stone, H.J., Collins, D.M., Preuss, M., Hardy, M.C., Rae, C.M.F., The effect of cooling rate from solution on the lattice misfit during isothermal aging of a Ni-base superalloy, Metallurgical and Materials Transactions A, 45 (5), pp. 2436-2444 (2014). 
  8. Dye, D., Stone, H.J., Watson, M., Rogge, R.B., Characterization of phase transformations and stresses during the welding of a ferritic mild steel, Metallurgical and Materials Transactions A, 45 (4), pp. 2038-2045 (2014). 
  9. Ramjaun, T., Stone, H.J., Karlsson, L., Kelleher, J., Moat, R.J., Kornmeier, J.R., Dalaei, K., Bhadeshia, H.K.D.H., Effect of interpass temperature on residual stresses in multipass welds produced using low transformation temperature filler alloy, Science and Technology of Welding and Joining, 19 (1), pp. 44-51 (2014). 
  10. Ramjaun, T.I., Stone, H.J., Karlsson, L., Kelleher, J., Ooi, S.W., Dalaei, K., Rebelo Kornmeier, J., Bhadeshia, H.K.D.H., Effects of dilution and baseplate strength on stress distributions in multipass welds deposited using low transformation temperature filler alloys, Science and Technology of Welding and Joining, 19 (6), pp. 461-467 (2014).

Other Publications

  1. Ramjaun, T., Stone, H.J., Karlsson, L., Kelleher, J., Moat, R.J., Kornmeier, J.R., Dalaei, K. and Bhadeshia, H.K.D.H., Effect of interpass temperature on residual stresses in multipass welds produced using low transformation temperature filler alloy. Science and Technology of Welding & Joining, 19(1):44–51 (2013).
  2. Collins, D.M., Yan, L., Marquis, E.A., Connor, L.D., Ciardiello, J.J., Evans, A.D., Stone, H.J., Lattice misfit during ageing of a polycrystalline nickel-base superalloy, Acta Materialia, 61(20):7791-7804, (2013).
  3. Choda, V., Bhowmik, A., Edmonds, I.M., Jones, C.N., Stone, H.J., A study of quaternary Cr-Cr2Ta alloys - Microstructure and mechanical properties, Materials Research Society Symposium Proceedings, 1516:275-281, (2013).
  4. Aveson, J.W., Tennant, P.A., Foss, B.J., Shollock, B.A., Stone, H.J., D'Souza, N., On the origin of sliver defects in single crystal investment castings, Acta Materialia, 61(14):5162-5171, (2013).
  5. Collins, D.M., Conduit, B.D., Stone, H.J., Hardy, M.C., Conduit, G.J., Mitchell, R.J., Grain growth behaviour during near-γʹ solvus thermal exposures in a polycrystalline nickel-base superalloy, Acta Materialia, 61(9):3378-3391, (2013).
  6. Bhowmik, A., Stone, H.J., A study on the influence of Mo, Al and Si additions on the microstructure of annealed dual phase Cr-Ta alloys, Journal of Materials Science, 48(8):3283-3293, (2013).
  7. Bhowmik, A., Pang, H.T., Edmonds, I.M., Rae, C.M.F., Stone, H.J., Effect of silicon additions on the high temperature oxidation behaviour of Cr-Cr 2Ta alloys, Intermetallics, 32:373-383, (2013).
  8. Pang, H. T., Edmonds, I. M., Jones, C.N., Stone, H.J., Rae, C.M.F., Effects of Y and La Additions on the Processing and Properties of a Second Generation Single Crystal Nickel-Base Superalloy CMSX-4®, 12th International Symposium on Superalloys, Seven Springs, PA,  Sep 9-13, pp.301-310, (2012).
  9. Aveson, J.W., Reinhart, G., Nguyen-Thi, H., Mangelinck-Noel, N. Tandjaoui, A. Billia, B., Goodwin, K., Lafford, T.A., Baruchel, J. Stone, H.J. D'Souza, N., Dendrite bending during directional solidification, 12th International Symposium on Superalloys, Seven Springs, PA,  Sep 9-13, pp.615-624, (2012).
  10. Yan, H.Y., Vorontsov, V.A., Coakley, J., Jones, N.G., Stone, H.J., Dye, D., Quaternary Alloying Effects and the Prospects for a New Generation of Co-base Superalloys, 12th International Symposium on Superalloys, Seven Springs, PA,  Sep 9-13, pp.705-714, (2012).
  11. Croxall, S.A., Hardy, M.C., Stone, H.J., Midgley, P.A., The Microstructure of RR1000 Nickel-Base Superalloy: The FIB-SEM Dual-Beam Approach, Proceedings of the 1st international conference on 3d materials science, 215-220, (2012).
  12. Bhowmik, A., Knowles, K.M., Stone, H.J., Microstructural evolution and interfacial crystallography in Cr-Cr 2Ta, Intermetallics, 31:34-47, (2012).
  13. Aveson, J.W., Reinhart, G., Billia, B., Nguyen-Thi, H., Mangelinck-Noël, N., Lafford, T.A., Vie, C.A., Baruchel, J., Stone, H.J., Observation of the initiation and propagation of solidification cracks by means of in situ synchrotron X-ray radiography, IOP Conference Series: Materials Science and Engineering, 33(1), art. no. 012040, (2012).
  14. Bhowmik, A., Stone, H.J., Microstructure and mechanical properties of two-phase Cr-Cr2Ta alloys, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 43(9):3283-3292, (2012).
  15. Pang, H.T., Stone, H.J., Rae, C.M.F., Zhang, L., Hobbs, R.A., Solution heat treatment optimization of fourth-generation single-crystal nickel-base superalloys, Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 43(9):3264-3282, (2012).
  16. Bhowmik, A., Jones, C.N., Edmonds, I.M., Stone, H.J., Effect of Mo, Al and Si on the microstructure and mechanical properties of Cr-Cr2Ta based alloys, Journal of Alloys and Compounds, 530:169-177, (2012).
  17. Pickering, E.J., Mathur, H., Bhowmik, A., Messé, O.M.D.M., Barnard, J.S., Hardy, M.C., Krakow, R., Loehnert, K., Stone, H.J., Rae, C.M.F., Grain-boundary precipitation in Allvac 718Plus, Acta Materialia, 60(6-7):2757-2769, (2012).

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