scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Characterization of microstructural changes due to prolonged thermal exposure of directionally solidified Ni-base super alloy CM 247LC using ultrasonic.

16 May 2018-Ultrasonics (Elsevier)-Vol. 90, pp 42-51
TL;DR: The microstructural changes of the fully heat treated alloy exposed at 980 °C for different hours of thermal exposure have been characterized using ultrasonic methods to non‐destructively characterize such detrimental changes in the microstructure that controls the mechanical properties and limits the life of components.
About: This article is published in Ultrasonics.The article was published on 2018-05-16. It has received 7 citations till now. The article focuses on the topics: Superalloy & Ultrasonic sensor.
Citations
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors presented the mechanism and modeling of fatigue crack initiation and propagation in CM186 LC directional solidified material of a first-stage gas turbine blade, which is used to investigate the crack initiation point.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of γ and η phases has been investigated on the physical and mechanical properties of a superalloy, and it was demonstrated that the optimization of heat treatment cycles of superalloys that can simultaneously have η and γ′ phases in their microstructure (such as IN939, IN792, IN740, GTD-111, Alloy 706, Rene 80, X-750, PWA1483, TMW, Nimocast 263) cannot be completed solely nondestructively by measurement of the physical properties.

10 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used ultrasonic non-destructive technique to assess the thermal degradation in a nickel-based superalloy and found that the non-linear parameters show hypersensitivity and high-credibility compared with the traditional linear parameters.

8 citations

Journal ArticleDOI
TL;DR: In this article , a mathematical model of energy storage based on dislocation entrapment is discussed, where the authors attributed high energy storage to the interaction between dislocation groups belonging to different slip bands and the destruction of short-range order (SRO) clusters.
Abstract: In the present study an attempt has been made to understand the high strain hardening in austenitic low-density steel using two full field measurements of temperature and strain on the sample during tensile deformation. Based on these measurements’ evolution of energy storage during deformation was calculated. High energy storage has been attributed to the interaction between dislocation groups belonging to different slip bands and destruction of short-range order (SRO) clusters. This in turn, dictates the range of the elastic stress field of slip bands. Furthermore, weak deformation heterogeneity ensued just after yield and continued with a fixed strain pattern up to facture. This did not result in macroscopic instability but manifested as microstructural heterogeneity in the form of micro-band and nano twins at later stages of deformation. A mathematical model of energy storage based on dislocation entrapment is discussed.

2 citations

Journal ArticleDOI
TL;DR: Using ammonium sulfate roasting laterite nickel ore-ammonium jarosite iron precipitation and hydrolysis preparation of Fe 2 O 3 -carbon thermal reduction preparation of LiFePO 4 /C process means, to achieve the ultimate goal of preparing LiFEPO 4 from laterite Nickel ore as discussed by the authors .
References
More filters
Journal ArticleDOI
TL;DR: A detailed discussion of data obtained over the past 15 years concerning the damping of mechanical vibrations in the kilocycle and megacycle range is given in this paper, where the dependence of the decrement and modulus change on the variables of frequency and strain-amplitude and many other parameters is compared with predictions of the dislocation theory developed in an earlier paper.
Abstract: A detailed discussion of data obtained over the past 15 years concerning the damping of mechanical vibrations in the kilocycle and megacycle range is given. The dependence of the decrement and modulus change on the variables of frequency and strain‐amplitude and many other parameters is compared with predictions of the dislocation theory developed in an earlier paper. Although general agreement is obtained, and many interesting quantitative results are found, it is not possible to say that the theory agrees everywhere since not all the necessary parameters are known well enough theoretically. A number of new experiments are suggested which may permit stronger conclusions to be made. This part may be read independently of the earlier paper by the reader who does not wish to follow the development of the theory in detail.

591 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a review of progress in quantitative non-destructive evaluation in the field of Optica Acta and Optica acta-Acta.
Abstract: (1985). Review of Progress in Quantitative Nondestructive Evaluation. Optica Acta: International Journal of Optics: Vol. 32, No. 7, pp. 747-747.

453 citations


"Characterization of microstructural..." refers background in this paper

  • ...[10] have shown that ultrasonic longitudinal velocity increases linearly with increase in the volume fraction of γ′ precipitates in the initial stages of thermal exposure of the Nimonic PE 16 alloy....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the long-term thermal stability of single crystal superalloys has been studied as a function of heat treatment and thermal exposure, and the microstructures and creep properties of the samples before and after longterm thermal exposures were characterized.
Abstract: The long-term thermal stability of CMSX-10 single crystal superalloys has been studied as a function of heat treatment and thermal exposure. The CMSX-10 alloys were subjected to long-term unstressed heat treatments at temperatures of 950 and 1050 °C for periods of 1000 and 10,000 h. The microstructures and creep properties of the samples before and after long-term thermal exposures were characterized. The γ′ coarsening was observed after all exposures and the formation of topologically close packed (TCP) phases was observed in both samples exposed at 1050 °C and the 10 kh exposure at 950 °C. High temperature creep tests were carried on these samples at 950 °C at an engineering stress of 310 MPa. The creep lives were found to deteriorate with the increase in exposure time and temperature as a result of the microstructural degradation. The coarsening of the γ′ precipitates was observed to be the main factor in the degradation of the properties.

213 citations

Journal ArticleDOI
TL;DR: In this paper, the evolution of the shape of a coherent, cubic precipitate as it grows by coarsening is studied. But the model assumes a precipitate of cubic phase with negative elastic anisotropy, and neglects any difference between the elastic constants of the precipitate and the matrix.

189 citations

Journal ArticleDOI
A. Hikata1, C. Elbaum1
TL;DR: In this paper, the effective tension term of a dislocation (string model) is represented as a power series in displacement gradients, and expressions for the amplitudes of the second and third harmonics of an ultrasonic wave introduced into a solid containing mobile dislocations are obtained.
Abstract: By representing the effective-tension term of a dislocation (string model) as a power series in displacement gradients, and retaining the first nonlinear term, expressions for the amplitudes of the second and third harmonics of an ultrasonic wave introduced into a solid containing mobile dislocations are obtained. In the case of the second harmonic, a lattice term, a dislocation term, and a cross term contribute to the amplitude and all three terms can be of comparable magnitude. In the case of the third harmonic, in a solid containing a reasonable density of mobile dislocations, the dislocation contribution to the amplitude is dominant and usually lattice effects can be neglected. Except in special circumstances, it is difficult to separate the three terms that contribute to the amplitude of the second harmonic, and dislocation dynamics, therefore, are more easily studied through the generation of third harmonics.

146 citations