Ryan Maclachlan

Loughborough University

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R.C. Thomson

Loughborough University

Michael Walls

Laboratoire de physique des Solides

V. N. Kornienko

Institute of Radio-Engineering and Electronics

Y. Y. Tse

Loughborough University

Stuart Robertson

Loughborough University

Jake W. Bowers

Renewable Energy Systems (United Kingdom)

Ali Abbas

Renewable Energy Systems (United Kingdom)

Thomas Fiducia

Renewable Energy Systems (United Kingdom)

Walajabad Sampath

Colorado State University

Marco Simonelli

University of Nottingham

Cooperative Institutions

Loughborough University

Renewable Energy Systems (United Kingdom)

University of Nottingham

Colorado State University

University of Warwick

Swansea University

Centre for Research in Engineering Surface Technology

Centre National de la Recherche Scientifique

National Renewable Energy Laboratory

United States University

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Microstructural Evolution of Boron Nitride Particles in Advanced 9Cr Power Plant Steels

Metallurgical and Materials Transactions A (2013)

Letian Li Ryan Maclachlan Mark A. Jepson R.C. Thomson

Precipitation hardening

10.1007/s11661-013-1642-x

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Citations (32)

The Effect of Simulated Post Weld Heat Treatment Temperature Overshoot on Microstructural Evolution in P91 and P92 Power Plant Steels

Advances in materials technology for fossil power plants : (2010)

Ryan Maclachlan J.J. Sanchez-Hanton R.C. Thomson

Abstract Creep strength enhanced ferritic (CSEF) steels, particularly modified 9Cr steels Grade 91 and 92, are increasingly used in advanced coal-fired power plants for header and steam piping construction. While these materials typically enter service after receiving a standard high-temperature normalizing treatment followed by lower temperature tempering to achieve optimal microstructure, practical situations like welding operations may expose components to additional heat treatment exceeding the Ac1, and potentially the Ac3, temperature before returning to tempering temperature. This research examines the effects of simulated post weld heat treatments (PWHT) on Grade 91 and 92 materials using dilatometer-controlled heating and cooling rates, with peak temperatures below Ac1, between Ac1 and Ac3, and above Ac3, followed by heat treatment at 750°C for 2 hours. Hardness measurements revealed significant reduction when exceeding the Ac1 temperature, while advanced electron microscopy, including electron back scatter diffraction, was employed to analyze changes in martensite laths and grain structure, along with detailed carbide size distribution analysis using both scanning and transmission electron microscopy. The findings are discussed in terms of how such PWHT overshoots might affect mechanical properties during high-temperature service.

Overshoot (microwave communication)

10.31399/asm.cp.am-epri-2010p0787

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High Speed 3-Dimensional Characterisation of Graded CdSeTe/CdTe PV Devices Using a Xenon Plasma-Focused Ion beam (PFIB)

V. N. Kornienko Stuart Robertson Ryan Maclachlan Tushar Shimpi Walajabad Sampath

3D electron backscatter diffraction (3D EBSD) was carried out using a Xe-PFIB on CdTe thin film solar cells, with a graded CdSeTe (CST) layer. Devices with different ranges of CST and CdTe thickness were investigated. Grain size, texture, coincident site lattice (CSL) boundaries through the film thickness were revealed by 3D EBSD and the elemental composition of the layers was studied using energy dispersive x-ray spectroscopy (EDS). Results show a reduction of (111) texture intensity and grain size when transitioning from CdTe to the graded (CST) layer. The CST has near randomised texture with weak (001) texture. Analysis of CSL boundaries showed that the CST layer in all devices has a lower frequency of Σ3 grain boundaries relative to other types of grain boundaries with a reduction of 15-22% from the CdTe to the CST layer.

Texture (cosmology)

Cadmium telluride photovoltaics

10.1109/pvsc43889.2021.9519098

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Citations (1)

Assessment and Quantification of Damage in the Grade 91 Steel Partially Transformed Zone

Advances in materials technology for fossil power plants : (2019)

John Siefert J.D. Parker Ryan Maclachlan Sabrina Yan R.C. Thomson

Abstract Damage in the grade 91 steel partially transformed zone of weld heat affected zones has historically been associated with many different types of microstructural features. Features described as being responsible for the nucleation of creep damage include particles such as laves phase, coarse M23C6, inclusions, nitrides, or interactions between creep strong and creep week grains, grain boundaries and potentially other sources. Few studies have attempted to link the observations of damage on scales of increasing detail from macro, to micro, to nano. Similarly, assessments are not made on a statistically relevant basis using 2D or 3D microscopy techniques. In the present paper, 2D assessment using scanning electron microscopy (SEM) and quantification techniques such as energy dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) are utilized in combination with 3D serial sectioning of large volumes using plasma focused ion beam milling (P-FIB) and simultaneous EDS to evaluate an interrupted cross-weld creep test. Moreover, the sample selected for examination was from a feature cross-weld creep test made using a parent material susceptible to the evolution of creep damage. The test conditions were selected to give creep brittle behaviour and the sample was from a test interrupted at an estimated life fraction of 60%. The findings from these evaluations provide perspective on the features in the microstructure responsible for the nucleation and subsequent growth of the observed damage.

Brittleness

10.31399/asm.cp.am-epri-2019p0022

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Citations (2)

Cracking behaviour of high-strength AA2024 aluminium alloy produced by Laser Powder Bed Fusion

Additive manufacturing (2022)

Giuseppe Del Guercio D.G. McCartney Nesma T. Aboulkhair Stuart Robertson Ryan Maclachlan

10.1016/j.addma.2022.102776

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Citations (40)

Effects of Successive CdCl₂ Treatments on the Texture of Thin Film CdTe Solar Cells

V. N. Kornienko Rachael Greenhalgh Kerrie Morris Ali Abbas Thomas Fiducia

The CdCl ₂ activation treatment is required for high efficiency CdTe solar cells. The treatment has many effects including increasing grain size and randomizing texture. Increasing grain size should result in higher efficiencies by minimizing grain boundary recombination. The use of metal-oxide layers to replace cadmium sulphide allows higher activation temperatures to be used resulting in larger grain sizes. However, use of these higher temperatures may affect the concentration of chlorine in the grain boundaries. Here we investigate the use of a first high temperature activation on closed space sublimated (CSS) Au/CdTe/TEC12D devices followed by a second optimized cadmium chloride treatment. We report on the effects on texture and grain size. Electron backscatter diffraction (EBSD) has been carried out using a Plasma Focused Ion Beam (PFIB) equipped with spin milling. Initial results indicate that the first higher temperature activation results in larger grains and a randomized texture.

Texture (cosmology)

Cadmium telluride photovoltaics

Cadmium chloride

10.1109/pvsc45281.2020.9300881

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Development of 9 wt.% Cr steels for next generation power plant

Ryan Maclachlan

There is a need to increase the thermal efficiency of coal fired power plants. High chromium ferritic steels have historically been used to manufacture steam pipes, tube and headers. Over the last forty years there has been a continuous development of the 9 – 12 wt. % chromium martensitic alloys which has allowed the service temperature to be increased from 510°C – 550°C1. There is now a high demand for Ultra Super Critical coal fired power plants which operate at 650°C and hence have an increased thermal efficiency. The aim of this research project was to develop a MarBN steel (Martensitic Steel Strengthened with Boron and Nitrides) with an optimised composition in order to allow MarBN to be used at 650°C. In order for MarBN to be used within high temperature applications it is vital to understand how microstructural changes can have an impact on their creep strength. This is a key area that the present research has focused upon. The long term creep strength of 9 wt. % chromium ferritic steels is derived from the stability of the microstructure over its service life, which has a direct relationship to the stability of the precipitates and the lath structure within the microstructure.

Lath

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