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temperature-dependent allotropic structure

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Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005441
EISBN: 978-1-62708-196-2
...Abstract Abstract This article presents a comprehensive collection of tables that list fundamental physical constants, standard atomic weights, melting points, atomic size parameters, heats of transition, thermal properties, temperature-dependent allotropic structures, pressure-dependent...
Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006221
EISBN: 978-1-62708-163-4
... dependent on temperature and pressure; these materials are called polymorphic , or allotropic for pure elements. The most commonly used allotropic element is iron, which undergoes a series of phase transformations as a function of temperature and pressure ( Fig. 3 ). At room temperature, iron has...
Book Chapter

Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003149
EISBN: 978-1-62708-199-3
... exhibit strong anisotropy because of two characteristics of the metal: zirconium has a hexagonal close-packed (hcp) crystal structure at room temperature, and it undergoes allotropic transformation to a body-centered cubic (bcc) structure at about 870 °C (1600 °F). The strong anisotropy profoundly...
Series: ASM Handbook
Volume: 2
Publisher: ASM International
Published: 01 January 1990
DOI: 10.31399/asm.hb.v02.a0001084
EISBN: 978-1-62708-162-7
... to a bcc structure at about 870 °C (1600 °F). Small amounts of impurities, particularly oxygen, strongly affect the transformation temperature ( Table 1 ). Variation in allotropic transformation temperature with oxygen content for unalloyed zirconium Table 1 Variation in allotropic transformation...
Series: ASM Handbook
Volume: 18
Publisher: ASM International
Published: 31 December 2017
DOI: 10.31399/asm.hb.v18.a0006367
EISBN: 978-1-62708-192-4
..., if not specified otherwise. Allotropes of Carbon Different structural forms of carbon, which is one of the most flexible in bonding configurations among all materials, have found a niche in a wide range of applications. High thermal conductivity ( Ref 2 ) and tunable electrical properties ( Ref 3 , Ref 4...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006250
EISBN: 978-1-62708-169-6
..., the positions and orientations of the new grains depend on the deformed grain structure. Consequently, the recrystallization microstructure may be equivalent to the deformation microstructure but also may differ from it, depending on the temperature and time of the recrystallization anneal. Recrystallized...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006286
EISBN: 978-1-62708-169-6
... symbol Definition α Low-temperature allotropic form of titanium with a hexagonal close-packed (hcp) structure; exists below β transus β High-temperature allotropic form with body-centered cubic (bcc) structure; exists at low temperature as metastable or stable phase in highly enriched alloys...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003084
EISBN: 978-1-62708-199-3
... form, a phenomenon known as polymorphism. When found in elemental solids, the condition is known as allotropy. The prevailing crystal structure depends on both the temperature and external pressure. For example, at atmospheric pressure, iron is bcc at temperatures below 912 °C (1674 °F), fcc...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001430
EISBN: 978-1-62708-173-3
... potential sources of iron contamination be avoided. Steel wire brushes should not be used for interpass cleaning of titanium weldments. Titanium is a single (α) phase material with a hcp crystal structure. However, an allotropic transformation occurs at temperatures above approximately 870 °C (1600 °F...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003085
EISBN: 978-1-62708-199-3
...”), depending on the conditions of state. State variables include composition, temperature, pressure, magnetic field, electrostatic field, gravitational field, and so forth. The term “phase” refers to that region of space occupied by a physically homogeneous material. However, there are two uses of the term...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003153
EISBN: 978-1-62708-199-3
..., small amounts of certain impurities, heat treatment, or plastic deformation. Several generally accepted structure-insensitive properties are the saturation induction ( B s ), resistivity (ρ), and Curie temperature ( T c ). These properties are largely dependent on the composition of the alloy selected...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003116
EISBN: 978-1-62708-199-3
.... A wide range of forging temperatures can be used for most of the common austenitic types because of the natural workability of austenite and the absence of allotropic transformation. The conventional 18-8 types often are forged at temperatures up to 1260 °C (2300 °F). However, the upper temperature limit...
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002460
EISBN: 978-1-62708-194-8
... defects. It discusses the relevance of the properties to design. The article describes the common means for increasing low-temperature strength and presents an example that shows structure-property relationships in nickel-base superalloys for high-temperature applications. The relationships...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004000
EISBN: 978-1-62708-185-6
... criteria. Alpha-two titanium aluminides retain an ordered microstructure at temperatures close to 1100 °C (2010 °F), termed the critical ordering temperature, with the actual temperature dependent on aluminum content and other alloying elements employed. Current commercially significant alpha-two...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005401
EISBN: 978-1-62708-196-2
... of these topics is briefly discussed in this section. Phase Equilibria/Phase Transformations Microstructure and texture evolution and control in titanium alloys is heavily dependent on the allotropic transformation from the hcp crystal structure (denoted as alpha phase) found at low temperatures to a bcc...
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005337
EISBN: 978-1-62708-187-0
... temperature of the alloys. As a result, the cast dendritic β structure is wiped out during the solid-state cooling stage, leading to an α + β platelet structure ( Fig. 2 ), which is also typical of β-processed wrought alloy. Further, the convenient allotropic transformation temperature range of most titanium...
Series: ASM Handbook
Volume: 1A
Publisher: ASM International
Published: 31 August 2017
DOI: 10.31399/asm.hb.v01a.a0006309
EISBN: 978-1-62708-179-5
... during heat treatment. The final structure consists of graphite within a matrix of pearlite, pearlite and ferrite, or ferrite (depending on the cooling rate after annealing). The temper carbon is not truly spherical (as in ductile iron) but consists of irregularly shaped aggregates. Fig. 1 Forms...
Series: ASM Handbook
Volume: 3
Publisher: ASM International
Published: 27 April 2016
DOI: 10.31399/asm.hb.v03.a0006226
EISBN: 978-1-62708-163-4
... the melt. Nucleation-Controlled Peritectic Structures The classical description of peritectic reactions postulates heterogeneous nucleation of β at the α-liquid interface at the peritectic equilibrium temperature, T p . Undercoolings of up to 4% of T p are required for the systems investigated...
Series: ASM Handbook
Volume: 4D
Publisher: ASM International
Published: 01 October 2014
DOI: 10.31399/asm.hb.v04d.a0005969
EISBN: 978-1-62708-168-9
... to produce temper carbon. When a white cast iron is heated for an extended period of time (up to about 60 h) at a temperature of 960 °C (1760 °F), the cementite decomposes into austenite and graphite. The final structure consists of graphite within a matrix of pearlite, pearlite and ferrite, or ferrite...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003086
EISBN: 978-1-62708-199-3
... it is frequently used, the term “property” connotes something that a material inherently possesses. More properly, a property should be regarded as the response of a material to a given set of imposed conditions (e.g., temperature and/or pressure). Material properties are the link between the basic structure...