Aluminum Alloys, Processing and Characterization: Characterization of Aluminium Alloys
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Dmitry Eskin, Brunel University
Monday 2:30 PM
February 24, 2020
Room: 1A
Location: San Diego Convention Ctr
Session Chair: Dmitry Eskin, Brunel University London
2:30 PM Introductory Comments
2:40 PM Invited
Stress Characterization of Bore-chilled Sand Cast Aluminum Engine Blocks in As-cast and T7 Condition with Application of Neutron Diffraction: Dimitry Sediako1; Joshua Stroh1; Glenn Byczynski2; Anthony Lombardi3; Anna Paradowska4; 1University Of British Columbia; 2Nemak USA/CAN; 3Nemak Canada Corporation; 4Australia's Nuclear Science and Technology Organisation
In an effort to improve vehicle fuel efficiency, aluminum (Al) alloys have been gaining upward momentum for use in automotive powertrain components such as engine blocks. Al alloys are lightweight and have good mechanical strength at engine operating temperatures; making them an suitable choice for engine block production. However, during the manufacturing process factors such as inhomogeneous cooling rates and/or coefficients of thermal expansion in multi-material castings can lead to the development of residual stress. This is of particular concern for the relatively thin cylinder bridges, which are exposed to large thermo-mechanical loading during engine operation. The casting process used at Nemak for I6 engine block production does not utilise cast-in liners and therefore may be also be suitable for future mass-produced linerless blocks. This paper utilizes neutron diffraction and SEM/EDS to determine how T7 heat treatment reduces the magnitude of residual stress in cast Al I6 engine blocks.
3:05 PM Invited
Molecular Dynamics Simulations of the Solidification of Pure Aluminium: Michail Papanikolaou1; Konstantinos Salonitis1; Mark Jolly1; 1Cranfield University
Despite the continuous and remarkable development of experimental techniques for the investigation of microstructures and the growth of nuclei during the solidification of metals, there are still unknown territories around the topic of nucleation during solidification. Such nanoscale phenomena can be effectively observed by means of Molecular Dynamics (MD) simulations which can provide a deep insight into the formation of nuclei and the induced crystal structures. In this study, MD simulations have been performed to investigate the solidification of Aluminium melt and the effects of process parameters such as the cooling rate and pressure on the final properties of the solidified material. A large number of Aluminium atoms have been used in order to investigate the grain growth over time solidification. The population of the Face Centred Cubic (FCC) and amorphous atom types has been recorded during the evolution of the process to illustrate the nanoscale mechanisms during solidification. Finally, the exothermic nature of the solidification process has been effectively captured by measuring the temperature of the Al atoms during grain formation.
3:30 PM
Nanoindentation and Cavitation-induced Fragmentation Study of Primary Al3Zr Intermetallics Formed in Al Alloys: Abhinav Priyadarshi1; Tungky Subroto2; Marcello Conte3; Koulis Pericelous4; Dmitry Eskin2; Paul Prentice5; Iakovos Tzanakis1; 1Oxford Brookes University; 2Brunel University London; 3Anton Paar TriTec SA; 4University of Greenwich; 5University of Glasgow
Mechanical properties of primary Al3Zr crystals and their in-situ fragmentation behaviour under the influence of a single laser induced cavitation bubble have been investigated using nanoindentation and high-speed imaging techniques, respectively. Linear loading of 10mN was applied to the intermetallics embedded in the Al matrix using a geometrically well-defined diamond nano-indenter to obtain the mechanical properties at room temperature conditions. Primary Al3Zr single crystals were also extracted by dissolving the aluminium matrix of an Al-3wt% Zr alloy. The extracted primary crystals were also subjected to cavitation action in deionized water to image the fracture sequence in real time. Fragmentation of the studied intermetallics was recorded at 500,000 frames per second. Results showed that the intermetallic crystals fail by brittle fracture mode most likely due to the repeatedly-generated shock waves from the collapsing bubbles. The results were interpreted in terms of fracture mechanics using the nanoindentation results. Keywords: Ultrasonic melt treatment, cavitation, fragmentation, intermetallic crystal, nanoindentation, high speed imaging
3:55 PM
In-situ Neutron Diffraction Solidification Analyses of Rare Earth Reinforced Hypoeutectic and Hypereutectic Aluminum-silicon Alloys: Joshua Stroh1; Dimitry Sediako1; David Weiss2; Vanessa Peterson3; 1University of British Columbia Okanagan; 2Eck Industries; 3ANSTO
Introduction of rare earth (RE) elements into aluminum (Al) alloys has been captivating the attention of manufactures who are interested in high temperature applications such as engine blocks and pistons. Recognised potential of RE additions such as cerium (Ce) to Al has lead to a new area of research focused on development of new alloys, targeting powertrain applications that require high temperature strength and creep resistance. In an attempt to further improve the mechanical properties of the Al-Ce system, this paper addresses the effects that RE additions have on the microstructure and kinetics of phase evolution during solidification of Al-Si alloys. This research presents the results of in-situ neutron diffraction solidification and SEM/EDS analyses performed for an Al-7%Si-3.5%RE and an Al-18%Si-8%RE alloy.
4:20 PM Break
4:35 PM
Influence of TiB2 Particles on Modification of Mg2Si Eutectic Phase in Al-Zn-Si-Mg-Cu Cast Alloys: Byung-Joo Kim1; Sung Su Jung1; Yong Ho Park2; Young Cheol Lee1; 1Korea institute of industrial technology; 2Pusan National University
In this study, the effect of TiB2 particles on the modification of eutectic phase in Al-Zn-Si-Mg-Cu system alloys is investigated. The microstructure showed that an excellent effect can be achieved after the addition of TiB2 particles. The morphology of eutectic Mg2Si changed from large Chinses script to fine polygonal shape with a significant reduction in size. Modified eutectic Mg2Si particles were investigated using an optical microscope and field emission scanning/transmission electron microscope, and it was confirmed that TiB2 particles acted as nucleation sites for the eutectic Mg2Si phase. Upon these results, a possible mechanism of eutectic Mg2Si phase modification by the addition of TiB2 particles is proposed.
5:00 PM
A Statistical Analysis to Study the Effect of Silicon Content, Surface Roughness, Droplet Size and Elapsed Time on Wettability of Hypoeutectic Cast Aluminum-silicon Alloys: Amir Kordijazi1; Swaroop Behera1; Omid Akbarzadeh2; Marco Povolo3; Pradeep Rohatgi1; 1University of Wisconsin, Milwaukee; 2University of Malaya; 3University of Bologna
In this study, the effect of silicon content, surface roughness, water droplet size, and elapsed time on contact angle (CA) of Aluminum-Silicon alloys were examined. To study wettability the static water contact angle was measured on a given sample using a goniometer. A laser confocal microscopy was used for measuring surface roughness. A full factorial design was utilized for the design of the experiment that includes all possible combinations of the independent factors and their levels (120 combinations). CA for each combination was measured three times, so in total 360 CA measurements were performed. To find the significant factors in CA variation and correlation between the significant factors and CA, Analysis of Variance (ANOVA) and Regression Analysis were performed, respectively. A significance level (α) of 0.05 was used for all statistical analyses. Contact angle values averaged 77° ± 5° with maximum value of 90º and minimum value of 64º, respectively. ANOVA results show that surface roughness and droplet size are significant factors. Regression analysis shows that CA increases by increasing surface roughness and water droplet size.
5:25 PM Cancelled
Aluminum Trace Elements Analyses using Epsilon 1 Meso EDXRF Technique: Hussain Al Halwachi1; 1Aluminium Bahrain (Alba)
The amount of alloying materials and trace elements available in Aluminum metal are usually measured by Optical emission spectroscopy (OES) technique, which is accurate and reliable method applied in most Aluminum smelters and downstream industries. In absence of OES machine, it is extremely difficult to decide the amount of alloying materials required for each Aluminum alloy, and certification of final Aluminum product cannot be carried out. In this study, a new analytical application is developed as a backup for OES using Epsioln1 Meso Energy Dispersive machine (EDXRF). The application is capable to measure the trace elements in Aluminum metal with high accuracy.