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order-disorder transformation

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Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2012
DOI: 10.31399/asm.tb.pdub.t53420171
EISBN: 978-1-62708-310-2
... decomposition intermediate phases order-disorder transformation spinodal transformation structures superlattice structures PHASE DIAGRAMS are often quite complex, with a number of different reactions occurring at different compositions and temperatures. In most cases, the appearance of several...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 January 2015
DOI: 10.31399/asm.tb.spsp2.t54410039
EISBN: 978-1-62708-265-5
... transformation under consideration here) or microstructural rearrangement without a phase change (for example, grain growth or particle coarsening) would occur in order to lower free energy to the minimum possible value. The free energy ( G ) per unit volume of a phase or combination of phases is defined in...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2012
DOI: 10.31399/asm.tb.pdub.t53420303
EISBN: 978-1-62708-310-2
.... Nickel alloys such as nickel-aluminum and nickel-titanium (~50 to 50 ratio) are also part of this alloy group, with a bcc parent phase. Because the transformations are diffusionless and lattice correspondence is maintained, order or disorder present in the parent phase is transferred to the martensite...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2012
DOI: 10.31399/asm.tb.pdub.t53420263
EISBN: 978-1-62708-310-2
... structure with respect to different crystal types, but such conditions must be externally formulated and imposed on the model. Equally, special relationships apply if the model is to be used to simulate order-disorder transformations. Fig. 13.2 Simple body-centered cubic structure sites consisting of...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 January 2015
DOI: 10.31399/asm.tb.tpmpa.t54480141
EISBN: 978-1-62708-318-8
... to a critical temperature, becomes disordered and melts as an alloy over a range of temperatures. Alloys based on the α 2 (Ti 3 Al) and γ (TiAl) ordered structure are termed titanium aluminides ( Ref 7.5 , 7.6 ). Because of the attractive high-temperature properties of these ordered structures...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2018
DOI: 10.31399/asm.tb.fibtca.t52430027
EISBN: 978-1-62708-253-2
... structure. When in a liquid state, metals have a highly disordered noncrystalline structure. However, when a molten metal or alloy cools and solidifies to form a bulk solid, it develops a crystalline structure with an ordered arrangement of atoms. In a crystalline solid there is a repetitive or periodic...
Series: ASM Technical Books
Publisher: ASM International
Published: 31 December 2020
DOI: 10.31399/asm.tb.phtbp.t59310029
EISBN: 978-1-62708-326-3
... classified as thermal or diffusive (reconstructive) transformations, because phase growth or decomposition is activated by the thermal (kinetic) energy of the atoms in the solid. Slow changes under near-equilibrium conditions are also reversible; the very same changes can take place in reverse order. That is...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2008
DOI: 10.31399/asm.tb.emea.t52240041
EISBN: 978-1-62708-251-8
.... However, in some systems, the ordering is so strong that it is stable up to the melting point. Fig. 3.6 Solid-solution structures An order-disorder transformation typically occurs on cooling from a disordered solid solution to an ordered phase. During this phase transformation, there is a...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 January 2015
DOI: 10.31399/asm.tb.spsp2.t54410113
EISBN: 978-1-62708-265-5
... etching. However, in contrast to acicular ferrite, the dispersed particles have a granular or equiaxed morphology. The ferrite crystals of the matrix, as shown by TEM ( Ref 7.10 , 7.11 , 7.30 ), are quite fine, on the order of a few micrometers in size; are equiaxed in shape; contain a high density of...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 July 2009
DOI: 10.31399/asm.tb.bcp.t52230179
EISBN: 978-1-62708-298-3
... melts congruently at 1219 °C (2225 °F). The gamma phase melts peritectically at 930 °C (1705 °F) and has a CsCl ordered cubic structure. The beta phase is a disordered solid solution stable above 620 °C (1150 °F). The solid solubility of beryllium in copper is sufficient to yield useful age-hardenable...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 1999
DOI: 10.31399/asm.tb.lmcs.9781627082914
EISBN: 978-1-62708-291-4
Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2012
DOI: 10.31399/asm.tb.lmub.t53550299
EISBN: 978-1-62708-307-2
... ordering temperature ( T c ). These ordered intermetallics usually exist in relatively narrow compositional ranges around simple stoichiometric ratios. Fig. 6.1 Atomic arrangements of conventional alloys and ordered intermetallic compounds. (a) Disordered crystal structure of a conventional alloy...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.tb.sap.t53000017
EISBN: 978-1-62708-313-3
... Antiphase-boundary (APB) energy in the presence of an ordered precipitate (γ′, γ″). The APB represents the energy needed for the dislocation to cut through the ordered precipitate, because cutting could result in disordering between the matrix and precipitate. Volume fraction of the precipitate (γ′, γ...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2002
DOI: 10.31399/asm.tb.mgppis.9781627082587
EISBN: 978-1-62708-258-7
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 2013
DOI: 10.31399/asm.tb.ems.t53730011
EISBN: 978-1-62708-283-9
... elements. The liquid state is intermediate between a gas and a crystal. Liquids do not have the high degree of order of crystals or the complete disorder of gases. For most materials, freezing causes a volume decrease of 1 to 6%. However, there are a few materials (water, silicon, germanium, bismuth...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2002
DOI: 10.31399/asm.tb.stg2.t61280025
EISBN: 978-1-62708-267-9
... a titanium-rich γ′ before transforming to η. Other types of intermetallic phases, such as δ orthorhombic Ni 3 Nb, or γ″ bct-ordered ( D 0 22 ) Ni 3 Nb strengthening precipitate, have been observed and contribute significantly to iron-nickel- and nickel-base superalloy strength. Gamma prime is an...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 January 2015
DOI: 10.31399/asm.tb.spsp2.t54410017
EISBN: 978-1-62708-265-5
... hardening tool steels in order to promote graphite formation for improved machinability ( Ref 3.2 ), and boron nitrides have been found to be effective in nucleating graphite in a medium-carbon steel containing 0.53% C ( Ref 3.3 ). Fig. 3.1 The Fe-C equilibrium diagram up to 7% carbon. Blue lines...
Series: ASM Technical Books
Publisher: ASM International
Published: 31 December 2020
DOI: 10.31399/asm.tb.phtbp.9781627083263
EISBN: 978-1-62708-326-3
Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2011
DOI: 10.31399/asm.tb.mnm2.t53060333
EISBN: 978-1-62708-261-7
... Metal or alloy system Composition range for transformation, wt% Change in crystal structure; parent → martensite(a) Internally faulted structures Co … fcc → hcp Co-Fe 0–3 Fe fcc → hcp Co-Ni 0–28 Ni fcc → hcp Cu-Al 10–11 Al bcc → hcp Cu-Zn 38–41.5 Zn ordered cubic...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2008
DOI: 10.31399/asm.tb.emea.t52240469
EISBN: 978-1-62708-251-8
...-temperature β phase is disordered, while the lower-temperature β′ phase is ordered ( Fig. 25.7 ). These alloys are easy to machine and hot form but are not very amenable to cold forming, because the β′ phase is brittle at room temperature. There is also a rapid reduction in the impact strength, with a...