Aluminum Alloys, Processing and Characterization: New and Optimized Aluminium Alloys II
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Dmitry Eskin, Brunel University
Wednesday 8:30 AM
February 26, 2020
Room: 1A
Location: San Diego Convention Ctr
Session Chair: Mehdi Lalpoor, Aleris; Alexis Miroux, Aleris
8:30 AM Introductory Comments
8:35 AM Invited
The Formation of Al6 (Fe, Mn) Phase Die-cast Al-Mg Alloys: Xiangzhen Zhu1; Shouxun Ji1; 1Brunel University London
In aluminium alloys, iron is a common impurity as it is unavoidably picked up in practice. The excessive Fe is strongly prone to form various intermetallic phases. These Fe-rich intermetallics are generally brittle and act as stress raisers to weaken the coherence with Al matrix, therefore decreasing elongation. However, Fe addition in Al-Mg alloys is beneficial because of the improvement in the yield strength with the scarification of ductility of die-cast aluminium alloys. The morphology of intermetallic phases has a vital effect on the properties of aluminium alloys. In the present work, the 3D morphology of Al6 (Fe, Mn) in die-cast Al-Mg-Mn alloys with different levels of Fe contents were revealed. The formation of Al6 (Fe, Mn) was also studied through crystal features and solidification behaviours.
9:00 AM
Spark Plasma Sintering of Graphene Nanoplatelets Reinforced Aluminium 6061 Alloy Composites: Mahmood Khan1; Rafi Ud Din2; Abdul Wadood1; Shahid Akhtar3; Syed Wilayat Husain1; Ragnhild Aune4; 1Institute of Space Technology, Islamabad; 2Pakistan Institute of Science and Technology; 3Norsk Hydro, Karmøy Primary Production; 4Norwegian University of Science and Technology (NTNU)
Over the years high performance lightweight aluminium matrix composites have, mainly due to their excellent mechanical properties, found wide applications in automobile and aerospace applications. In the present study, Graphene NanoPlatelets based reinforced aluminium alloy Al6061 composites have been prepared through spark plasma sintering with four different loadings, i.e. 0.1 wt.%, 0.5 wt.%, 1 wt.% and 3 wt.%. Through property characterisation of the obtained composites, it was established that a higher content of nano reinforcement had a strong effect on the resulting microstructure, as well as on the electrical conductivity that proved to increase due to uniform distribution of the graphene network around the grains. An increase in the hardness and compressive strength was also obtained, and the strengthening mechanism is discussed. A 2-dimensional physical model based on the bridging effect of graphene nanoplatelets in a composite matrix is presented, and its correlation with experimental results is discussed.
9:25 AM
Effects of Mn and Mo Micro-additions on Al-Zr-Sc-Er-Si Mechanical Properties: Shipeng Shu1; Anthony De Luca1; David Seidman1; David Dunand1; 1Northwestern University
Dilute Al-Zr-Sc-Zr-Si alloys strengthened by coherent L12 Al3(Sc,Er,Zr) nanoprecipitates have potential applications at temperatures higher than 400 °C. In this work, individual and synergistic effects of micro-addition of 0.25 at.% Mn and/or 0.10 at.% Mo to a dilute Al-0.08Zr-0.014Sc-0.008Er-0.09Si (at.%) alloy were investigated using a combination of techniques such as SEM, TEM, APT, and mechanical testing after various heat treatments. Mn and Mo introduce solid-solution strengthening, contributing to both ambient-temperature strength and elevated-temperature creep resistance. Aging at 400 °C leads to formation of L12 core-shell nanoprecipitates, with Mn partitioning at the core, and Mo partitioning to both the core and precipitate/matrix interface. Mn-modified L12 precipitates exhibit higher number density, while Mo-modified L12 precipitates show improved coarsening resistance. Formation of coarse Al/Si/Mn-rich α-precipitates in the Mn-containing alloy contribute moderate precipitation hardening, but consumes Mn/Si solutes in the matrix, leading to decreased creep resistance of the alloy at overaged conditions.
9:50 AM
Nanotreating High-zinc Al-Zn-Mg-Cu Alloy by TiC Nanoparticles: Jie Yuan1; Min Zuo2; Maximilian Sokoluk3; Gongcheng Yao1; Shuaihang Pan3; Xiaochun Li3; 1Department of Materials Science and Engineering, University of California Los Angeles; 2University of Jinan; 3Department of Mechanical and Aerospace Engineering, University of California Los Angeles
High-zinc Al-Zn-Mg-Cu alloys offer the highest strength among all aluminum alloys mostly due to high-volume precipitates after heat treatment. However, the high zinc content makes the alloys more sensitive to hot cracking and stress corrosion cracking during solidification and solid state processing. Recently, a revolutionary method, Nanotreating, becomes significant in metals processing by introducing ceramic nanoparticles into metals. It is an emerging method to modify the microstructures (both primary and secondary phases) during solidification, deformation and heat treatment. In this work, In-situ TiC nanoparticles were added into Al-8.6Zn-2.8Mg-1.8Cu alloy to study the nanotreating effects. The grain size of the as-cast alloy has been reduced significantly from 272.3 μm to about 30.4 μm by 1 vol.% TiC nanoparticles. The size of remaining large secondary phase after heat treatment were reduced significantly as well. Furthermore, the hardness was enhanced. Nanotreating is promising as an effective approach to modify the microstructure, relieve the manufacturing difficulty, and enhance the properties of the high-zinc Al-Zn-Mg-Cu alloys for widespread applications.
10:15 AM Break
10:30 AM
Microstructure and Mechanical Response of Artificially Aged Al-Mg-Si Alloys: Experiments and Modeling: Yoojin Kim1; Sharvan Kumar1; 1Brown University
Three Al-Mg-Si alloys with different Mg and Si content were selected to isolate the effect of alloying elements on microstructure evolution during isothermal aging and the consequential influence on mechanical response. Microstructure evolution in these alloys was investigated by transmission electron microscopy (TEM) and precipitate type, morphology and size distribution were quantified; an analytical model for precipitation kinetics of β" precipitates with a cylindrical morphology and an aspect ratio obtained from experiment, has been developed to predict precipitates size distribution, volume fraction and residual Mg and Si content in solid solution and compared to experimental results. Single crystal micropillars were obtained in the T6 condition and compressed to obtain CRSS and early stage hardening. The precipitation model developed above is coupled to a strength model to predict the CRSS as a function of alloy chemistry and crystallographic orientation and findings are compared to experiments.
10:55 AM
Effect of Zn Additions on the Mechanical Properties of High Strength Al-Si-Mg-Cu Alloys: Sungsu Jung1; Soo Been Hwang1; Byung Joo Kim1; Yong Ho Park2; Young Cheol Lee1; 1KITECH(Korea Institute of Industrial Technology); 2Pusan National University
In this study, the effect of Zn additions on the mechanical properties of Al-Si-Mg-Cu alloys was investigated. From the results, it has been found that the formation of Mg-Zn intermetallic compounds is considered to be the main reason for the sharp changes in the mechanical properties of this alloy system. The microstructure showed that Mg-Zn intermetallic compounds were formed between the reinforcement phase like Mg2Si phase and the matrix became more brittle as the amount of Zn addition was increased. Upon these results, we could confirm that the formation of Mg-Zn intermetallic compounds and brittle matrix are the main reasons for the remarkable changes in the mechanical properties of this alloy system.
11:20 AM
Utilization of 3D Printed Materials in Expendable Pattern Casting Process: Dika Handayani1; Nicole Wagner1; Victor Okhuysen1; Michael Seitz1; Kyle Garibaldi1; 1Cal Poly Pomona
While lost foam casting process offers advantages of producing complex parts without the needs of parting line, draft and core, this process requires long lead time and only works for high volume applications due to the tooling requirements. With recent developments of 3D printing technology, the limitations of this process can be mitigated. Utilization of 3D printed materials instead of foam will allow the production of pattern materials at lower cost and shorter lead time, and also, low-volume production. The objective of this study was to explore the feasibility of producing cast parts using expendable casting process with 3D printed materials (PLA, ABS, and PVA) as patterns. These materials were printed in a shape of fluidity spiral with different sizes and in-fill designs, and were then poured with A356 Aluminum. Results showed that this process can be used as an alternative method to produce cast aluminum components.