Journal ArticleDOI
A general mechanism of martensitic nucleation: Part I. General concepts and the FCC → HCP transformation
Gregory B. Olson,Morris Cohen +1 more
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In this paper, the stacking fault energy is shown to consist of both volume energy and surface energy contributions, and when the volume energy contribution is negative, the fault energy decreases with increasing fault thickness such that fault energy associated with the simultaneous dissociation of an appropriate group of dislocations can be zero or negative.Abstract:
Consideration of the martensitic nucleation process as a sequence of steps which take the particle from maximum to minimum coherency leads to the hypothesis that the first step in martensitic nucleation is faulting on planes of closest packing. It is further postulated that the faulting displacements are derived from an existing defect, while matrix constraints cause all subsequent processes to occur in such a way as to leave the fault plane unrotated, thus accounting for the observed general orientation relations. Using basic concepts of classical nucleation theory, the stacking fault energy is shown to consist of both volume energy and surface energy contributions. When the volume energy contribution is negative, the fault energy decreases with increasing fault thickness such that the fault energy associated with the simultaneous dissociation of an appropriate group of dislocations (e.g. a finite tilt boundary segment) can be zero or negative. This condition leads to the spontaneous formation of a martensitic embryo. For the specific case of the fcc → hcp martensitic transformation in Fe-Cr-Ni alloys, the defect necessary to account for spontaneous embryo formation at the observedM
s temperatures may consist of four or five properly spaced lattice dislocations. Such defects are considered to be consistent with the known sparseness of initial martensitic nucleation sites.read more
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Future Trends on Displacive Stress and Strain Induced Transformations in Steels
TL;DR: In this article, the authors summarize the fundamental knowledge about stress and strain induced transformations, both in fully austenitic or in multiphase structures, pointing out the issues that need further research.
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Cavitation erosion resistance of Fe-26Mn-6Si-7Cr-1Cu shape memory alloy
N. D. Long,J. H. Zhu +1 more
TL;DR: In this article, the cavitation erosion of low stacking fault energy Fe-26Mn-6Si-7Cr-1Cu shape memory alloy has been investigated in water using an ultrasonic vibratory apparatus, and compared with the behaviour of 0Cr13Ni5Mo stainless steel.
Journal ArticleDOI
Multi-phase field modeling in TRIP steels: Distributed vs. average stability and strain-induced transformation of retained austenite
Maria-Ioanna T. Tzini,John S. Aristeidakis,Peter I. Christodoulou,Alexis T. Kermanidis,Gregory N. Haidemenopoulos,Daniel Krizan +5 more
TL;DR: In this paper, an integrated approach is developed, for the description of microstructural evolution of a TRIP700 steel during processing, using multi-phase field modeling, and two models are employed to assess RA stability, through M S σ, M S calculations, and strain-induced transformation kinetics of dispersed RA upon plastic deformation.
Journal ArticleDOI
Structural Phase Transformation in Ni-Hf and Ni-Ti Systems Studied by Molecular Dynamics Simulation
Jia Hao Li,B. X. Liu +1 more
TL;DR: In this article, molecular dynamics simulations are performed on the Ni-Hf and Ni-Ti solid solution models, respectively, and the invariant crystalline plane in the transformation is identified to be (0110) hep and the orientation relationships are deduced to be(0001) hep ∥(001) fco and [1000] hcp II [110] fco, respectively.
Journal ArticleDOI
Analysis of Electron Channeling Contrast of Stacking Faults in fcc Materials
TL;DR: In this paper, a series of electron channeling contrast (ECC) images taken as a function of sample tilt at ~0.1° increments across the (111) Kikuchi band were analyzed under different channeling conditions.
References
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The Determination of the Elastic Field of an Ellipsoidal Inclusion, and Related Problems
TL;DR: In this paper, it is shown that to answer several questions of physical or engineering interest, it is necessary to know only the relatively simple elastic field inside the ellipsoid.
Book
Theory of Dislocations
John Price Hirth,Jens Lothe +1 more
TL;DR: Dislocations in Isotropic Continua: Effects of Crystal Structure on Dislocations and Dislocation-Point-Defect Interactions at Finite temperatures.
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The scientific papers
TL;DR: Physical and psychosocial factors associated with psychostimulant use in a nationally representative sample of French adolescents: Specificities of cocaine, amphetamine, and ecstasy use are studied.
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The crystallography of martensite transformations II
J.S Bowles,J.K Mackenzie +1 more
TL;DR: In this paper, the total strain in a martensite transformation was derived from the orientation relationship and the component strains, together with the correspondence, and the dimensions of the initial and final structures.
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