Perspectives on Titanium Science and Technology
TL;DR: In this paper, the complexity and variety of fundamental phenomena in this material system with a focus on phase transformations and mechanical behaviour are discussed. And the challenges that lie ahead in achieving these goals are delineated.
About: This article is published in Acta Materialia.The article was published on 2013-02-01. It has received 1797 citations till now.
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18 Oct 2021
TL;DR: In this article, the authors used the double Burgers orientation relation (DBOR) to predict texture memory in hexagonal metals such as cubic and hexagonal steels and Ti and Zr alloys.
Abstract: Texture memory is a phenomenon in which retention of initial textures occurs after a complete cycle of forward and backward transformations, and it occurs in various phase-transforming materials including cubic and hexagonal metals such as steels and Ti and Zr alloys. Texture memory is known to be caused by the phenomena called variant selection, in which some of the allowed child orientations in an orientation relationship between the parent and child phases are preferentially selected. Without such variant selection, the phase transformations would randomize preferred orientations. In this article, the methods of prediction of texture memory and mechanisms of variant selections in hexagonal metals are explored. The prediction method using harmonic expansion of orientation distribution functions with the variant selection in which the Burgers orientation relationship, {110}β//{0001}α-hex β//21¯1¯0α-hex, is held with two or more adjacent parent grains at the same time, called “double Burgers orientation relation (DBOR)”, is introduced. This method is shown to be a powerful tool by which to analyze texture memory and ultimately provide predictive capabilities for texture changes during phase transformations. Variation in nucleation and growth rates on special boundaries and an extensive growth of selected variants are also described. Analysis of textures of commercially pure Ti observed in situ by pulsed neutron diffraction reveals that the texture memory in CP-Ti is indeed quite well predicted by consideration of the mechanism of DBOR. The analysis also suggests that the nucleation and growth rates on the special boundary of 90° rotation about 21¯1¯0α-hex should be about three times larger than those of the other special boundaries, and the selected variants should grow extensively into not only one parent grain but also other grains in α-hex(hexagonal)→β(bcc) transformation. The model calculations of texture development during two consecutive cycles of α-hex→β→α-hex transformation in CP-Ti and Zr are also shown.
2 citations
TL;DR: In this paper , a spinodal decomposition in a Ti-Nb-based titanium alloy via aging treatment was obtained in a wide temperature range of about 500 K and a high strength-to-modulus ratio of about 1.5% by a reversible crystal ordering mechanism.
2 citations
Dissertation•
01 Nov 2017
TL;DR: In this paper, the influence of cutting parameters on the surface integrity, subsurface microstructure, tool wear and fatigue performance for finish milling of Ti-5Al-5Mo-5V-3Cr landing gear components was investigated.
Abstract: A detailed investigation into the influence of cutting parameters on the surface integrity, subsurface microstructure, tool wear and fatigue performance for finish milling of Ti-5Al-5Mo-5V-3Cr landing gear components. Low cost, small scale testing methodologies have been developed to replicate complex machining strategies employed in aerospace manufacturing, to understand and develop an improved processing window. Machinability trials identifieded the influence of cutting speed (Vc), feed per tooth (fz) and surface generation rates (SGR) on surface roughness and subsurface deformation. The detrimental impact of fz can be offset somewhat by comparable increases in Vc. The subsequent reduction in imposed cutting forces, increased
coolant delivery and improved chip evacuation achieves moderate responses in surface integrity and subsurface deformation. Severe plastic deformation at the near
surface, exacerbated by increased cutting parameters, is accommodated through dislocation slip along basal, prismatic and pyramidal planes of primary alpha
grains. Deformation modes, which are intensified by increased tool wear. A transition from abrasive to adhesive tool wear mechanisms have been identified and shown to be accelerated by increased fz. Through the application of a bespoke four point bend test rig, low cycle fatigue testing at R=0.1, has proposed some important observations for fatigue performance of machined high strength titanium allows. Cycles
to failure were shown to be reduced for identical applied stress for increased SGR. Fatigue cracks has been identified within the severe plastic deformation region of the subsurface, as a result of machining. Initiation was produced through quasi-cleavage along dislocation slip planes of alpha grains and propagated in a mixed mode, significantly influenced by bulk beta grains. A competing mechanism between initiation influenced by machining damage and propagation retardation as a result of machining induced compressive residual stresses has been postulated.
2 citations
2 citations
TL;DR: In this paper , a TWIP-enhanced Zr-13.8Nb-0.7Hf alloy was designed by electron-to-atom ratio for strain-hardening and ductility enhancements.
2 citations
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TL;DR: In this paper, the influence of alloy chemistry, thermomechanical processing and surface condition on these properties is discussed and various surface modification techniques to achieve superior biocompatibility, higher wear and corrosion resistance.
4,113 citations
TL;DR: A group of alloys that exhibit “super” properties, such as ultralow elastic modulus, ultrahigh strength, super elasticity, and super plasticity, at room temperature and that show Elinvar and Invar behavior are described.
Abstract: We describe a group of alloys that exhibit “super” properties, such as ultralow elastic modulus, ultrahigh strength, super elasticity, and super plasticity, at room temperature and that show Elinvar and Invar behavior. These “super” properties are attributable to a dislocation-free plastic deformation mechanism. In cold-worked alloys, this mechanism forms elastic strain fields of hierarchical structure that range in size from the nanometer scale to several tens of micrometers. The resultant elastic strain energy leads to a number of enhanced material properties.
795 citations
15 Mar 1998-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the thermomechanical processing of beta titanium alloys in general and high temperature deformation mechanisms, microstructure control during TMP, and final mechanical properties in particular are reviewed.
Abstract: Thermomechanical processing (TMP) is associated with two major requirements: (i) to produce usable shapes through primary working (ingot breakdown) and secondary mill operations (hot rolling or forging) and (ii) to optimize mechanical properties through microstructure control during the different stages of the thermomechanical process. This paper reviews the thermomechanical processing of beta titanium alloys in general and high temperature deformation mechanisms, microstructure control during TMP, and final mechanical properties in particular.
709 citations
660 citations