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Publications
Publications (23)
Ni-based superalloys with enhanced oxidation resistance at high temperatures are crucial for next-generation gas turbine engines. A new polycrystalline Ni-based superalloy (C19) that combines improved microstructural stability with environmental resistance has been developed. Its oxidation resistance has been determined through measurements of the...
The microstructure and properties of alloy Haynes 282 produced through laser powder bed fusion were investigated as a function of the post-deposition heat-treatment. Scanning electron microscopy and X-ray diffraction were utilized to characterize the microstructure, whilst electro-thermal mechanical testing was used to evaluate the tensile and cree...
The microstructure and properties of alloy Haynes 282Haynes 282 produced through laser powder bed fusionLaser powder bed fusion were investigated as a function of the post-deposition heat-treatmentHeat-treatments. Scanning electron microscopy and X-ray diffraction were utilized to characterize the microstructure, whilst electro-thermal mechanical t...
Recently, a new High Temperature Environmental Testing (HTET) methodology has been described which combines cyclic oxidation with the addition of synthetic sea salt. The current investigation aims to further understand the effects of synthetic sea salt deposition on the oxidation behavior of a second-generation nickel-base single-crystal superalloy...
A detailed analysis of the response of as-cast third-generation single-crystal nickel-based superalloy CMSX-10K® to solution heat treatment (SHT) has been carried out, alongside an SHT optimization exercise. The analysis was conducted through microstructural characterization, differential scanning calorimetry, and compositional homogeneity measurem...
The effects of temperature, dwell and environment on the fatigue crack growth behaviour of two nickel base turbine disc superalloys RR1000 and Udimet 720Li are presented in the present paper. Fatigue tests were carried out at room temperature in air using a 20 Hz sinusoidal loading waveform and at elevated temperatures of 650 and 725 degrees C in b...
Whereas the effect of contaminants in causing hot corrosion has been extensively studied at temperatures up to 1000°C, this paper describes a systematic study of the effects of various salt deposits on the cyclic oxidation of CMSX-4o in air at temperatures above 1000°C. The alloy was tested both in the bare and in the platinum aluminised (Pt-Al) co...
The effect of Si additions between 0 and 15 at.% on the microstructure and oxidation resistance of Cr–Ta alloys has been studied. After annealing at 1300 °C for 500 h, the microstructures of the alloys were observed to consist predominantly of a Cr-rich solid solution and a Cr2Ta Laves phase, with the Si partitioning preferentially to the Laves pha...
The effects of yttrium and lanthanum additions on the processing and properties of a second generation single crystal nickel-base turbine blade superalloy CMSX-4® are investigated. The additions of Y and La at 20 ppm Y+La did not have a significant effect on the as-cast microstructure; while at 65 and 350 ppm, the appearance of Y and La-rich phases...
The optimization of the solution heat treatment (SHT) of fourth-generation single-crystal nickel-base superalloys LDSX-6B and LDSX-6C is presented. The methodological approach to optimizing the SHT process is particularly highlighted. Differential scanning calorimetry (DSC) measurements and electron-probe microanalysis (EPMA) mapping were carried o...
The demand for higher engine operating temperatures to improve aeroengine efficiency has meant that increasing levels of alloying additions are being added to single-crystal nickel-base superalloys for turbine blades applications. Whilst better mechanical and environmental performance may be obtained with these alloying additions, they also destabi...
The phase equilibria and oxidation resistance of alloys lying near the Cr-rich end of the Cr- Ta-Si system have been investigated. Samples were prepared by arc-melting and homogenized at 1300°C for 500hrs. Identification of the phases present and their compositions were carried out using x-ray diffraction and electron probe micro-analysis and the t...
Turbine discs experience a range of temperature and load conditions in service, but the increasing operating temperatures expected for new, more efficient engine designs, mean that increasingly their time-dependent fatigue response is of more and more importance. A variety of alloying and heat treatment approaches have now been developed to improve...
ABSTRACT An assessment of the effects of microstructure on room temperature fatigue threshold and crack propagation behaviour has been carried out on microstructural variants of U720Li, i.e. as-received U720Li, U720Li-LG (large grain variant) and U720Li-LP (large intragranular coherent ′ variant). Fatigue tests were carried out at room temperature...
An assessment of the effects of microstructure on room temperature fatigue threshold and crack propagation behaviour has been carried out on microstructural variants of U720Li, i.e. as-received U720Li, U720Li-LG (large grain variant) and U720Li-LP (large intragranular coherent ?' variant). Fatigue tests were carried out at room temperature using a...
An analysis of the microstructure of the interdendritic regions in an as-cast third generation single-crystal nickel-base
superalloy CMSX-10K has been carried out using automated serial sectioning with sequential focused ion beam (FIB) milling
and image capture of the secondary electron image in a combined FIB–scanning electron microscope (SEM). Tw...
An assessment of the effects of microstructure on room temperature fatigue crack initiation and short crack propagation in a Ni-base superalloy is presented. The assessment was carried out on microstructural variants of U720Li, including as-received U720Li, U720Li-LG (large grain variant) and U720Li-LP (large intragranular coherent γ′ variant). Fat...
The microstructure and fatigue performance of three subsolvus heat treated nickel based superalloys for turbine disc applications are reported. The alloy variants studied are RR1000, N18 and Udimet 720 low interstitial (U720Li), with the latter tested both in a standard and large grain variant (LG). Their microstructures are examined in terms of gr...
An assessment of the effects of microstructure on fatigue crack initiation and short crack growth in a turbine disc nickel-base superalloy at 650 °C in air is presented. U720Li and microstructural variants of U720Li, i.e. U720Li-LG (large grain variant) and U720Li-LP (large intragranular coherent γ′ precipitate variant) have been assessed by uninte...
This paper presents the results of high temperature fatigue tests carried out in air at 725°C on four different materials: N18, RR1000, Udimet 720Li (U720Li) and U720Li Large Grain (U720Li LG) variant. The influence of composition, sub-solvus heat treatments, together with varied cooling rates on grain size and gamma prime size and distribution on...
An assessment of the effects of microstructure and operating parameters on both crack initiation and propagation of short fatigue cracks is presented. The assessment was carried out on RR1000, U720Li and microstructural variants of U720Li. Fatigue tests were carried out at room temperature (20 Hz sinusoidal cycling) and at 650 °C (1–1–1–1 trapezoid...
