Powder Metallurgy of Light, Reactive and Other Non-ferrous Metals: Session I
Sponsored by: TMS Powder Materials Committee
Program Organizers: Ma Qian, Royal Melbourne Institute of Technology; James Paramore, Texas A&M University; David Yan, San Jose State University
Monday 2:00 PM
November 2, 2020
Room: Virtual Meeting Room 24
Location: MS&T Virtual
Session Chair: James Paramore, United States Army Research Laboratory; David Yan, San Jose State University
2:00 PM Keynote
By-products from Laser-material Interactions in Laser Powder Bed Fusion of Metal Powders: Aijun Huang1; Haopeng Shen1; Xinhua Wu1; 1Monash University
Aiming to improve the process reliability and to facilitate the certification of LPBF, this work investigates the by-products, vapour plume and spatters found in LPBF with a focus on the crucial process parameters that have been least studied so far. The vapour-plume is found to mainly consist of nanoparticles that follow the gas flow easily. Sever laser-plume can lead to undesirable laser-plume attenuation at low gas flow, which results in large irregular lack-of-fusion defects and reduces the tensile strength. On the other hand, mechanical test results showed that spatter contamination reduces the tensile strength slightly but more significantly the fatigue properties. However, using unique LPBF scanning strategies in this work, the fatigue performance of spatter-contaminated samples can be improved significantly to the same level of samples without spatter. The knowledge obtained and methods developed in this research can be applied to facilitate the certification of LPBF productions of failure-critical components.
2:30 PM Keynote
Influence of Powder Characteristics, Temperature and Cooling Rate on the Development of the Properties in Ni-Superalloys Processed Using Powder Hot Isostatic Pressing: Moataz Attallah1; Alessandro Sergi1; James MacDonald1; 1University of Birmingham
A powder HIP manufacturing route for several Ni-superalloy has been investigated. Several studies were performed focusing on processing-microstructure-property relationships. Scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD) techniques were used to assess the influence of powder characteristics, heat treatment and HIP parameters. High-temperature mechanical testing was also performed. Excellent tensile properties have been obtained with HIPped material, however, poor creep performance raises concerns regarding the use of powder HIPped Ni-superalloys for long duration aero-engine components. Certain chemistry changes may make a modified version of the alloy more suitable. The HIP process requires further refinement with Ni-superalloys to allow a good balance of high-temperature properties to be obtained, especially through the use of cooling rate and outgassing procedures.
3:00 PM Invited
Hot Isostatic Pressing of Niobium-based Refractory Alloy Powders: Calvin Mikler1; Brian Welk1; Benjamin Georgin1; Todd Butler2; Noah Philips3; Hamish Fraser1; 1The Ohio State University; 2Air Force Research Laboratory; 3ATI Specialty Alloys and Components
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, pre-alloyed HDH WC-3009 and PREP C-103 powders 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.
3:20 PM
Diffusion Behavior and Mechanical Properties of the Aluminum / Tungsten Metallic System: Ammar Alyasari1; Raghavan Srinivasan1; 1Wright State University/ The Middle Technical University-Baghdad
The binary aluminum-tungsten system shows three intermediate compounds, Al12W, Al5W, and Al4W. This presentation will cover the results of a study of diffusion behavior in this system, using powder compacts of pure aluminum and pure tungsten. Prior studies have shown that Al12W forms as a thin layer on the tungsten particles, and the amount of Al5W formed is negligible. Through heat treatment, it is possible to control the relative amounts of the phases that are formed. It is important to understand mechanisms that control the diffusional transformation since the intermetallics are formed at the interface between the aluminum and tungsten powder particles. The Broeder diffusion theory was used to analyze the diffusion behavior in this system. The interface layer thickness and chemical composition were measured using high-resolution SEM with EDS. The effect of the formation of the intermediate phases on the mechanical properties of the composite was also evaluated.
3:40 PM
Deformation-free Refinement of Prior β Grain Size in Powder Metallurgical Titanium Alloys: Daniel Lewis1; James Paramore2; Brady Butler2; Griffin Turner1; Trevor Hastings1; 1Texas A&M University; 2U.S. Army Research Laboratory
Due to high cost of titanium alloys, there is a significant incentive to develop near net shape processes to improve utilization of titanium, such as powder metallurgy (PM). However, titanium PM often results in parts with a coarse microstructure, which compromises mechanical properties when compared to traditionally produced wrought parts. One method of creating PM titanium parts with fine microstructures and wrought-like properties is Hydrogen Sintering and Phase Transformation (HSPT). HSPT has been shown to produce excellent tensile and fatigue properties, but has a hierarchical structure with coarse prior β grains, which may limit performance. This study aimed to examine non-deformation-based means to refine the prior β grains in order to further improve mechanical properties. To this end, various quenching and heat treatments were incorporated into HSPT. Additionally, thorough characterization of microstructure and mechanical behavior were used to evaluate the efficacy of these processing methodologies.
4:00 PM
The Role of Processing and Texture on the Dynamic Mechanical Behavior of Powder Metallurgy Processed Ti-6Al-4V: James Paramore1; Brady Butler1; Matthew Dunstan1; Hongjoo Rhee2; Haitham El Kadiri2; Wilburn Whittington2; Shiraz Mujahid2; 1U.S. Army Research Laboratory; 2Mississippi State University
Hydrogen sintering and phase transformation (HSPT), a powder metallurgy process, has been previously shown to produce desirable microstructures in Ti-6Al-4V components with corresponding excellent static and fatigue tensile properties. In the current study, three microstructures produced by HSPT and one produced by traditional wrought processing were tested under compression at strain rates of 0.001, 0.1, and >1000 s-1. The wrought condition exhibited the best toughness at 0.001 s-1, but had the worst performance at both 0.1 and >1000 s-1 strain rates. From microstructural analyses, it is shown that the wrought condition had strong crystallographic texture consistent with hot rolling above the β-transus temperature. It is proposed that this texture made the wrought material susceptible to relatively early-onset shear banding at all but the lowest strain rate. This texture does not form in the HSPT microstructures.