Properties of Textured Titanium Alloys

This study attempts to develop Ti-Nb alloys with elastic moduli that approach that of human bone. The experimental results reveal that the microstructure of a Ti-Nb alloy that contains 14 mass% Nb consists of and phases, with phase being the dominant one. The proportion of the phase decreases gradually as the Nb content increases, and the microstructure becomes completely the phase when the Nb content exceeds 34 mass%. Moreover, the ! phase can be detected using XRD and TEM in alloys with a Nb content from 30 to 34 mass%. Over the Nb range studied (14 to 40 mass%), the elastic modulus decreases from 14 to 26 mass% Nb, and then increases to a maximum at 34 mass% Nb, before falling again as Nb content is increased further. The elastic modulus of the Ti-Nb alloys is closely related to the microstructure (or Nb content) of the alloys. The fall in the elastic modulus with the increasing Nb content from 14 to 26 mass% is associated with a gradual decrease in the proportion of the phase in the microstructure, while the precipitation of the ! phase accounts for the increase in the elastic modulus over the intermediate range of Nb (30 to 34 mass%). The tensile strength of Ti-Nb alloys increases slightly from 14 to 26 mass% Nb, and then increases markedly with a Nb content of up to 34 mass%, before falling drastically as Nb content is increased further. A similar pattern was obtained for 0.2% proof stress, while the elongation vs. %Nb curve was just the reverse of the T.S. vs. %Nb curve, as expected. A Ti-Nb alloy with a relatively high Nb content (above 36 mass%) is preferred to other compositions for use in medical implants with a reduced stress shielding effect.

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“…Different phases (, and !) have different elastic modulus, they are estimated to be related by E ; 1:5E 35) and E ! ; 2:0E .…”

Section: Tem and Sadp (Selected Area Diffraction Pattern)mentioning

confidence: 99%

Composition/Phase Structure and Properties of Titanium-Niobium Alloys

2003

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“…For titanium and its alloys, for example, both first-tier properties such as yield strength and ductility and second-tier properties such as fracture toughness and fatigue response are affected. [1][2][3] Texture in titanium alloys may be developed as a result of deformation, dynamic/static recrystallization, grain growth, or phase transformation. [4,5] To date, a large amount of research has been conducted to understand the development of deformation textures due to processes such as sheet rolling, extrusion, and forging.…”

Section: Introductionmentioning

confidence: 99%

Variant Selection During Cooling after Beta Annealing of Ti-6Al-4V Ingot Material

Sargent

Kinsel

Pilchak

et al. 2012

Metall Mater Trans A

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The selection of alpha variants during the cooling of Ti-6Al-4V from the beta-phase field was investigated. For this purpose, samples with a coarse, columnar beta-grain structure with a h100i fiber texture were extracted from an as-cast production-scale ingot. The alpha variants in the as-cast samples as well as those produced during several successive beta-annealing treatments were determined using electron backscatter diffraction (EBSD). The EBSD results indicated that a subset of the 12 possible variants was developed within each grain; the specific variants were a function of the cooling rate after beta heat treatment. Moreover, the generation of similar variants during successive heat treatments involving an identical cooling rate suggested a noticeable memory effect. The variant selection process was rationalized based on calculations of the strain associated with the beta-to-alpha transformation. These calculations revealed that the overall aggregate strain approached zero in both the as-cast condition as well as after beta heat treatment, suggesting the occurrence of a long-range self-accommodation mechanism.

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“…Unalloyed titanium and titanium alloys comprise a class of material for which texture can be unusually strong and therefore is very important with regard to mechanical properties [4,5]. The tendency to form strong textures results principally from the low symmetry of the hcp crystal structure which characterizes many titanium alloys at low-temperatures, the limited number of slip and twinning systems that can be activated to accommodate imposed deformation of hcp crystals, and the allotropic transformation of titanium from the bcc beta phase (at high temperatures) to the hcp alpha phase (at low temperatures).…”

Section: Introductionmentioning

confidence: 99%

Continuous Performance in the Fur Seal: A Bridge to Extended Waking in Humans

Siegel¹,

Lyamin²

2007

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air Force Research Laboratory SPONSORING/MONITORING AGENCY ACRONYM(S) SPONSORING/MONITORING AGENCY REPORT NUMBER(S) AFRL-RX-WP-TP-2008-4352 DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. SUPPLEMENTARY NOTESPaper submitted to the ASM Handbook, Vol. 22-Modeling and Simulation: Processing of Metallic Materials. PAO Case Number: WPAFB 08-5083; Clearance Date: 18 Aug 2008. The U.S. Government is joint author of this work and has the right to use, modify, reproduce, release, perform, display, or disclose the work. Paper contains color. ABSTRACTThe development of crystallographic texture, the preferred orientation of grains in a polycrystalline aggregate, during thermomechanical processing (TMP) can play an important role with regard to the secondary-forming response (e.g., deep drawing of sheet) and service performance (e.g., strength, elastic modulus, ductility, fracture toughness) of metallic materials. Crystallographic texture, or simply texture for succinctness, may arise as a result of large-strain deformation, dynamic/static recrystallization, grain growth, or phase transformation [1]. A second form of anisotropy, mechanical texturing or mechanical fibering, refers to the alignment of microstructure, inclusions, etc., during deformation processes and may also affect mechanical properties such as ductility and fracture toughness. This latter form of texture is not discussed in the present article.

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Properties of Textured Titanium Alloys

Cited by 44 publications

References 29 publications

Composition/Phase Structure and Properties of Titanium-Niobium Alloys

Composition/Phase Structure and Properties of Titanium-Niobium Alloys

Variant Selection During Cooling after Beta Annealing of Ti-6Al-4V Ingot Material

Continuous Performance in the Fur Seal: A Bridge to Extended Waking in Humans

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