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CAMM To Present at TMS 2020

CAMM researchers will be presenting their latest results at TMS 2020 in San Diego, California.  

Room Temperature Interface Sliding in TIMETAL-407
Presenter: Zachary T. Kloenne

Authors: Zachary Kloenne1, Gopal Viswanathan1, Matt Thomas2, Michael Loretto3,Hamish Fraser11The Ohio State University; 2TIMET; 3University of Birmingham

Symposium: Advanced Characterization Techniques for Quantifying and Modeling Deformation
Date: 02/24/2020
Time: 11:30 AM - 12:00 PM
Location: San Diego Convention Ctr - Room Theater A-2

Abstract: Titanium alloys are excellent candidates for aerospace applications owing to their high strength to weight ratio. Alpha/beta titanium alloys are used in nearly all sections of the aircraft, including the fuselage, landing gear, and wing. Ti-0.85Al-3.9V-0.25Si-0.25Fe (Ti-407) is an excellent candidate for alloy applications requiring excellent machinability and increased energy absorption. Through a combination of electron backscattered diffraction (EBSD) and diffraction contrast imaging, it was determined that the alloy deforms significantly by <c+a> slip in both hard and soft grains. More surprisingly, Ti-407 has also been shown to deform by interface sliding during room temperature tensile tests. The nature of this sliding has been investigated using in situ straining in a scanning electron microscope (SEM). The alpha/beta interface was explored using atom probe tomography (APT) and high resolution scanning transmission electron microscopy (HRSTEM) to provide insight on the cause of interface sliding.

Surface Characterization of IN718 Powder Stock and Influence on Net-shape HIP Microstructure
Presenter: Benjamin Georgin

Authors: Benjamin Georgin1; Victor Samarov2; Hamish Fraser11The Ohio State University; 2LNT
Symposium: Additive Manufacturing: Alternative Processes (Beyond the Beam) (Poster Session)
Date: 02/24/2020
Time: Monday PM
Location: San Diego Convention Ctr - Room Sails Pavilion

Abstract: Net-shape hot isostatic pressing (HIP) is a promising manufacturing route for highly alloyed materials such as Ni-base alloys which are difficult to conventionally process. The application and performance of net-shape HIP components has been limited by characteristics of prior particle boundary (PPB) networks. These form as a direct result of oxygen contamination of powder stock which is highly dependent on the atomization processes and powder storage conditions. Clean atomization processes such as plasma rotating electrode process (PREP) minimize oxygen contamination. Oxygen is present both in the bulk and on the surface of the powders. In alloy 718, a nanoscale oxide layer forms on the powder surface due to the high concentration of oxide forming elements present. This study provides an in-depth characterization of surface oxidation of powder stock as well as the effect of powder size distribution (PSD) on PPB networks and microstructure in net-shape HIP components.

Evolution of Microstructure in Net-shape HIP IN718 with Improved Fatigue Performance
Presenter: Benjamin Georgin

Authors: Benjamin Georgin1; Victor Samarov2; Hamish Fraser1; 1The Ohio State University; 2LNT
Symposium: Advancing Current and State-of-the-Art Application of Ni- and Co-based Superalloys: Ni-based Superalloys – Structure & Properties
Date: 02/25/2020
Time: 5:20 PM - 5:40 PM
Location: San Diego Convention Ctr - Room 11B

Abstract: The buy-to-fly ratio of Ni-base alloys can be improved by manufacturing components via net-shape hot isostatic pressing (HIP). Historically, the fatigue performance and high temperature ductility of direct-HIP parts has been inadequate when compared with conventional processing routes. Prior particle boundary (PPB) networks form as a result of oxygen contamination of powder stock and drive fatigue performance in these materials. They serve to pin grain boundaries and provide an easy fracture path for cracks resulting in intergranular failure. Recent studies have shown that direct HIP of high purity IN718 powder stock results in a fully recrystallized microstructure with the PPB network lying within the grain interior, reducing the tendency for crack propagation. The reduced oxygen content in the powders increases the oxide interparticle separation which allows recrystallized nuclei at powder boundaries to bypass the PPB network. Homogeneous strain distributions in the powders promote uniform recrystallization and suppress abnormal grain growth.

Hot Isostatic Pressing of WC-3009 Niobium-Based Refractory Alloy
Presenter: Calvin Mikler

Authors: Calvin Mikler1, Benjamin Georgin1, Brian Welk1, Gopal Viswanathan1, Kevin Chaput2, Hamish Fraser1; 1The Ohio State University; 2Air Force Research Laboratory
Symposium: Refractory Metals 2020
Date: 02/25/2020
Time: 10:50AM - 11:10 AM
Location: Cardiff | Marriott Marquis Hotel

Abstract: Niobium-based WC-3009 (Nb-30Hf-9W wt%) is a single-phase bcc refractory alloy designed as a candidate replacement for the still commonly utilized C-103 (Nb-10Hf-1Ti wt%) alloy. While WC-3009 exhibits superior high-temperature mechanical properties compared with C-103, fabrication is economically prohibitive, and the alloy was not employed in any capacity. In this study, aliquots of pre-alloyed hydride-dehydrideWC-3009 powder were canned and subsequently consolidated via hot isostatic pressing (HIP). This effort was performed to identify key alloy attributes that drive processability through HIP such that higher strength Nb-based refractory alloys can be utilized. Backscattered electron (BSE) imaging and electron backscattered diffraction (EBSD) analysis revealed the degree of recrystallization and recovery substructure formation. Transmission electron microscopy (TEM) coupled with x-ray energy dispersive spectroscopy (XEDS) were employed to analyze second phase precipitation behavior and dislocation substructures. The results indicated that hot isostatic pressing is a viable method of processing high performance Nb-based refractory alloys.

(Invited) Exploration of Nano-scaled Metastable Phases in Metastable Beta Titanium Alloys Using Advanced Electron Microscopy and Atom Probe Tomography
Presenter: Yufeng Zheng

Authors: Yufeng Zheng1; Dong Wang2; Stoichko Antonov3; Dipankar Banerjee4; Rajarshi Banerjee5; Yunzhi Wang6; Hamish Fraser6; 1University of Nevada, Reno; 2Xi’an Jiaotong University; 3University of Science and Technology Beijing; 4Indian Institute of Science; 5University of North Texas; 6Ohio State University
Symposium: Metastable Phases and Phase Equilibria: Towards Designing the Next Generation of Alloys — Session I
Date: 02/26/2020
Time: 9:10 AM - 9:40 PM
Location: San Diego Convention Ctr– Room 31A

Abstract: Metastable beta titanium alloys have attracted a significant amount of attention in recent years, due to the fact that the microstructure of metastable beta titanium alloys is very sensitive to thermo-mechanical processes, and therefore its performance can be manipulated by accurately controlled processing conditions. In these alloys, the phase transformation pathways and deformation modes can be significantly influenced by the nano-scaled metastable phases. For example, the size and number density of alpha precipitates in Ti-5Al-5Mo-5V-3Cr can be modified by the pre-formed nano-scaled metastable isothermal omega phase in parent beta phase. In this work, four different nano-scaled metastable phases in the as-quenched or aged metastable beta titanium alloys, including athermal and isothermal omega phase, O' phaseand O'' phase, have been systematically studied using advanced electron microscopy and atom probe tomography. The formation mechanism of each phase and their potential influence on microstructure evolution and deformation will be introduced.

Development of New Ti-64 Modified Alloys for Additive Manufacturing with Columnar to Equiaxed Transition
Presenter: NevinTaylor

Authors: Nevin Taylor1; Brian Welk1; Zachary Kloenne1; Andrew Baker2; Hamish Fraser1; 1The Ohio State University; 2Boeing
Symposium: Additive Manufacturing: Materials Design and Alloy Development II
Date: 02/26/2020
Time: 4:35 PM - 4:55 PM
Location: San Diego Convention Ctr – Room 6F

Abstract: There are a number of defects associated with the additive manufacturing of titanium alloys that must still be addressed. One such issue is the formation of coarse columnar grains that form parallel to the growth/deposition direction leading to anisotropic properties. In this research, the use of alloying elements, specifically the Beta-eutectoid stabilizers, have been shown to induce a columnar to equiaxed transition through modification of the solidification mechanism. A Laser Engineered Net Shaping (LENS) AM device with two powder hoppers has been used to create gradient builds by varying the alloying elements of interest, narrowing down the composition of the columnar to equiaxed transition and demonstrating the effect of composition on microstructure. Subsequent heat treatments have been investigated to optimize the mechanical properties of the new Ti-64 modified alloys, which show promising results for use in wide-spread applications.

Microstructure and Texture in Cryomilled and Spark Plasma Sintered Ti Grade 2
Presenter: Jiri Kozlik

Authors: Jiri Kozlik1; Petr Harcuba1; Josef Strasky1; Hanka Becker2; Tomas Chraska3; Milos Janecek1; 1Charles University; 2TU BergakademieFreiberg; 3Czech Academy of Sciences
Symposium: Advanced Characterization Techniques for Quantifying and Modeling Deformation
Date: 02/27/2020
Time: 5:00 PM - 5:20 PM
Location: San Diego Convention Ctr - Room 31B

Abstract: Titanium Grade 2 was processed by cryogenic milling and subsequently sintered by field assisted sintering technique (FAST) with the aim of creating and preserving the ultra-fine grained microstructure. Microstructural investigation was performed after both milling and sintering, a transmission Kikuchi diffraction was used to characterize the individual milled powder particles.
The milled powders showed significant grain refinement down to 50 nm. We assume this to be the equilibrium grain size resulting from the balance of deformation, recovery and dynamic recrystallization. A rolling-like texture was also found in the milled particles as a result of the deformation mechanism during milling.
The grain size of the sintered samples ranged from 0.5 to 10 μm, depending on the sintering conditions. Although the grains are completely recrystallized, a texture similar to the powder was also found in these samples as a result of packing of the powder particles and continuous static recrystallization.