FMW Composite Systems Inc.

Bridgeport, WV, United States

FMW Composite Systems Inc.

Bridgeport, WV, United States
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McReynolds K.S.,UES, Inc. | Tamirisakandala S.,FMW Composite Systems Inc.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

Isothermal oxidation experiments in air were performed on Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) with a bimodal microstructure in the temperature range 811 K to 922 K (538 °C to 649 °C) for up to 500 hours, and α-case depths were quantified using metallography. Alpha-case depth followed a parabolic variation with time. Alpha-case depths in excess of 10 μm formed above 811 K (538 °C) and 100-hour exposures. An activation energy of 244 kJ/mol was estimated for diffusion of oxygen in the α phase of Ti-6242. © 2011 The Minerals, Metals & Materials Society and ASM International.


Ravi V.A.,California State Polytechnic University, Pomona | Rogers S.,California State Polytechnic University, Pomona | Malek M.,California State Polytechnic University, Pomona | Surmenian D.,California State Polytechnic University, Pomona | And 6 more authors.
JOM | Year: 2011

Musculoskeletal and craniofacial implants, and their interactions with the human body, are a very important area of medicine today. Aging populations and rapidly escalating health care costs make the study of implant-body interactions increasingly urgent. One of the major impediments to long-term durability of implant materials is the issue of aseptic loosening, i.e., inflammatory response against the prosthetic metal and metal debris produced by its corrosion. In this research summary, we discuss the corrosion behavior of a new class of boron-containing titanium alloys in physiologically relevant media. In addition, the suitability of these alloys from a mechanical perspective will also be discussed along with implications for alloy design.


Roy S.,Indian Institute of Science | Suwas S.,Indian Institute of Science | Tamirisakandala S.,FMW Composite Systems Inc. | Tamirisakandala S.,Air Force Research Lab | And 2 more authors.
Acta Materialia | Year: 2011

Hypoeutectic boron addition (0.1 wt.%) to Ti-6Al-4V is known to cause significant refinement of the cast microstructure. In the present investigation, it has been observed that trace boron addition to Ti-6Al-4V alloy also ensures excellent microstructural homogeneity throughout the ingot. A subdued thermal gradient, related to the basic grain refinement mechanism by constitutional undercooling, persists during solidification for the boron-containing alloy and maintains equivalent β grain growth kinetics at different locations in the ingot. The Ti-6Al-4V alloy shows relatively strong texture with preferred components (e.g. ingot axis||[0 0 0 1] or [1 0 1̄0]) over the entire ingot and gradual transition of texture components along the radius. For Ti-6Al-4V-0.1B alloy, significant weakening characterizes both the high-temperature β and room-temperature α texture. In addition to solidification factors that are responsible for weak β texture development, microstructural differences due to boron addition, e.g. the absence of grain boundary α phase and presence of TiB particles, strongly affects the mechanism of β → α phase transformation and consequently weakens the α phase texture. Based on the understanding developed for the boron-modified alloy, a novel mechanism has been proposed for the microstructure and texture formation during solidification and phase transformation. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


McEldowney D.J.,University of Dayton | Tamirisakandala S.,FMW Composite Systems Inc. | Miracle D.B.,Air Force Research Lab
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2010

The Ti-6Al-4V (Ti-64) alloys modified with two levels of boron (1B and 1.7B (wt pct)) representing hypoeutectic and hypereutectic compositions, produced via a prealloyed powder metallurgy approach, were subjected to various standard heat treatments of Ti-64 to study the microstructural evolution and its influence on tensile properties. Boron-modified Ti-64 (Ti-64B) alloys exhibited differences in microstructural response to heat treatment compared to that of Ti-64 due to variations in constituent phase fractions and the influence of TiB on the beta-to-alpha phase transformation kinetics. The tensile elastic modulus of Ti-64B alloys increased nearly linearly with the boron content (or TiB volume fraction) and the increase could be satisfactorily predicted with an isostrain rule of mixtures (ROMs) and the Halpin-Tsai model. The Ti-64-1B possessed a good combination of tensile strength (1200 to1370 MPa) and ductility (10 to 13 pct), while Ti-64-1.7B exhibited high strength (1300 to 1695 MPa) and modest ductility (2 to 3.5 pct). Coarse primary TiB particles present in Ti-64-1.7B were found to initiate premature failure. Strength modeling revealed that load sharing by the micron-sized TiB whiskers provides the major contribution for the increase in yield strength. © 2010 The Minerals, Metals & Materials Society and ASM International.


Roy S.,Indian Institute of Science | Suwas S.,Indian Institute of Science | Tamirisakandala S.,FMW Composite Systems Inc. | Srinivasan R.,Wright State University | Miracle D.B.,Air Force Research Lab
Materials Science and Engineering A | Year: 2012

Boron addition to conventional titanium alloys below the eutectic limit refines the cast microstructure and improves mechanical properties. The present work explores the influence of hypoeutectic boron addition on the microstructure and texture evolution in Ti-6Al-4V alloy under β extrusion. The β extruded microstructure of Ti-6Al-4V is characterized by shear bands parallel to the extrusion direction. In contrast, the extruded Ti-6Al-4V-0.1B alloy shows a regular β worked microstructure consisting of fine prior β grains and acicular α-lamellae with no signs of the microstructural instability. Crystallographic texture after extrusion was almost identical for the two alloys indicating the similarity in their transformation behavior, which is attributed to complete dynamic recrystallization during β processing. Microstructural features as well as crystallographic texture indicate dominant grain boundary related deformation processes for the boron modified alloy that leads to homogeneous deformation without instability formation. The absence of shear bands has significant technological importance as far as the secondary processing of boron added alloys in (α. +. β)-phase field are concerned. © 2012 Elsevier B.V.


Srinivasan R.,Wright State University | Tamirisakandala S.,FMW Composite Systems Inc.
Scripta Materialia | Year: 2010

Trace boron addition to several titanium alloys results in a reduction in the as-cast grain size by an order of magnitude. TiB needles are observed along the prior beta grain boundaries and not the grain interior in these alloys, indicating that TiB needles are not sites for the heterogeneous nucleation of beta grains. This study seeks to understand the influence of the growth rate R on microstructure evolution and grain refinement in Ti-6Al-4V-0.1B alloy using directional solidification experiments and microstructural characterization. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


A method of increasing the thermal conductivity and decreasing the electrical resistivity of a titanium alloy. Boron is introduced into the titanium alloy to produce TiB precipitates. The TiB precipitates are then aligned in a direction of metal flow by hot metalworking.


A method of increasing the thermal conductivity and decreasing the electrical resistivity of a titanium alloy. Boron is introduced into the titanium alloy to produce TiB precipitates. The TiB precipitates are then aligned in a direction of metal flow by hot metalworking.


Patent
FMW Composite Systems Inc. | Date: 2013-09-11

A method and apparatus for producing titanium metal powder from a melt. The apparatus includes an atomization chamber having an inner wall that is coated with or formed entirely of CP-Ti to prevent contamination of titanium metal powder therein. The inner surfaces of all components of the apparatus in a flow path following the atomization chamber may also be coated with or formed entirely of CP-Ti.


Sinha V.,Air Force Research Lab | Sinha V.,UES, Inc. | Srinivasan R.,Wright State University | Tamirisakandala S.,Air Force Research Lab | And 2 more authors.
Materials Science and Engineering A | Year: 2012

The superplastic behavior of Ti-6Al-4V-0.1B sheet was evaluated. The strain rate sensitivity (m) is ≥0.47 in the temperature range 775-900. °C and at strain rate, ε̇=10-5 to 10-3 s-1. The material exhibits tensile elongations. >. 200% in the temperature range 725-950. °C at ε̇=3×10-4 s-1. The optimum superplastic forming temperature is 900. °C, which is similar to conventional Ti-6Al-4V. However, a lower flow stress is needed in the case of Ti-6Al-4V-0.1B. The superplastic deformation mechanism is suggested from estimates of activation energy to be grain boundary sliding (GBS) accommodated by dislocation motion along grain boundaries at ε̇=10-4 s-1 and is diffusion-controlled dislocation climb at ε̇=10-3 s-1. Microstructural observations also confirm that GBS is the operating deformation mechanism at 900. °C and ε̇=3×10-4 s-1. © 2011 Elsevier B.V.

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