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- Research outputs 2014 to 2021 (3)
- Department of Mechanical and Materials Engineering: Faculty Publications (2)
- ENGS 88 Honors Thesis (AB Students) (1)
- Manufacturing & Industrial Engineering Faculty Publications and Presentations (1)
- Materials Science and Engineering Faculty Publications and Presentations (1)
Articles 1 - 9 of 9
Full-Text Articles in Engineering
Electroshock Treatment Dependent Microstructural Evolution And Mechanical Properties Of Near-Β Titanium Alloy Manufactured By Directed Energy Deposition, Haojie Guo, Pu Liu, Xunpeng Qin, Yanli Song, Dongsheng Qian, Lechun Xie, Liqiang Wang, Lai-Chang Zhang, Lin Hua
Electroshock Treatment Dependent Microstructural Evolution And Mechanical Properties Of Near-Β Titanium Alloy Manufactured By Directed Energy Deposition, Haojie Guo, Pu Liu, Xunpeng Qin, Yanli Song, Dongsheng Qian, Lechun Xie, Liqiang Wang, Lai-Chang Zhang, Lin Hua
Research outputs 2014 to 2021
Effects of electroshock treatment (EST) on the microstructural evolution and mechanical properties of near-β titanium alloy (Ti-55531) formed by directed energy deposition (DED) was studied in this work. With the increase in EST time, the average hardness of specimen decreased from 426 HV to 316 HV, and the fracture strain increased significantly, which was attributed to the uniform dispersion of α phase along grain boundaries and inside the β grains. After EST, the texture intensity decreased in terms of the orientation distribution function (ODF), which was ascribed to the redistribution of α phase. Moreover, more atomic vacancies and lattice distortion …
Effect Of Crystal Quality On Twinning Stress In Ni–Mn–Ga Magnetic Shape Memory Alloys, Andrew Armstrong, Peter Müllner
Effect Of Crystal Quality On Twinning Stress In Ni–Mn–Ga Magnetic Shape Memory Alloys, Andrew Armstrong, Peter Müllner
Materials Science and Engineering Faculty Publications and Presentations
Low twinning stress (TS) is a prerequisite for magnetic shape memory functionality in ferromagnetic martensites. We compare Ni50Mn28Ga22 (nominal at.%) single crystals from four different producers to reveal the effect of crystal quality on the TS. Near the reverse martensite transformation, the TS is generally low, about 1 MPa, regardless of mosaicity of up to 1.7° and chemical composition deviations of up to 2 at.% of Mn. Pure type I and type II twin boundaries occur in crystals with smooth chemical composition gradients. The corresponding temperature dependences of TS follow universal linear trends with the …
The Thermal Conductivity Of Polar Firn, Simon Oster
The Thermal Conductivity Of Polar Firn, Simon Oster
ENGS 88 Honors Thesis (AB Students)
A custom device is designed, validated, and used to make the first reported direct measurements of the effective thermal conductivity of polar firn. The firn cores spanned depths from 8 to 47 m from an undisturbed site near the South Pole in Antarctica. The thermal conductivity varies with depth, with values ranging from 0.617 to 1.018 W/mK, and the associated thermal diffusivities range from 20.95 to 25.68 m2/a. Density and porosity contribute to the variation in thermal conductivity but cannot be used to completely prescribe the conductivity. Initial analyses indicate that firn microstructure relates to conductivity through Euler-Poincaré …
Additive Manufacturing And Mechanical Properties Of The Dense And Crack Free Zr-Modified Aluminum Alloy 6061 Fabricated By The Laser-Powder Bed Fusion, Abhishek Mehta, Le Zhou, Thinh Huynh, Sharon Park, Holden Hyer, Shutao Song, Yunali Bai, D. Devin Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn
Additive Manufacturing And Mechanical Properties Of The Dense And Crack Free Zr-Modified Aluminum Alloy 6061 Fabricated By The Laser-Powder Bed Fusion, Abhishek Mehta, Le Zhou, Thinh Huynh, Sharon Park, Holden Hyer, Shutao Song, Yunali Bai, D. Devin Imholte, Nicolas E. Woolstenhulme, Daniel M. Wachs, Yongho Sohn
Mechanical Engineering Faculty Research and Publications
For additive manufacturing such as laser powder bed fusion (LPBF), commercial aluminum alloy (AA) 6061 is typically considered unsuitable due to formation of solidification cracking and/or excessive porosity. In this study, to improve buildability/printability of AA6061, 1 wt% of Zr was alloyed to produce Zr-modified AA6061 by LPBF. Powders of unmodified and Zr-modified AA6061 were produced by gas atomization, and utilized as a feed-stock for the LPBF to fabricate specimens for microstructural examination and mechanical testing. The as-built unmodified AA6061 exhibited poor printability due to formation of cracks and porosity in the microstructure regardless of LPBF parameters. However, the Zr-modified …
Part-Scale Thermal Simulation Of Laser Powder Bed Fusion Using Graph Theory: Effect Of Thermal History On Porosity, Microstructure Evolution, And Recoater Crash, Reza Yavari, Ziyad Smoqi, Alex Riensche, Ben Bevans, Humaun Kobir, Heimdall Mendoza, Hyeyun Song, Kevin Cole, Prahalada Rao
Part-Scale Thermal Simulation Of Laser Powder Bed Fusion Using Graph Theory: Effect Of Thermal History On Porosity, Microstructure Evolution, And Recoater Crash, Reza Yavari, Ziyad Smoqi, Alex Riensche, Ben Bevans, Humaun Kobir, Heimdall Mendoza, Hyeyun Song, Kevin Cole, Prahalada Rao
Department of Mechanical and Materials Engineering: Faculty Publications
Flaw formation in laser powder bed fusion (LPBF) is influenced by the spatiotemporal temperature distribution – thermal history – of the part during the process. Therefore, to prevent flaw formation there is a need for fast and accurate models that can predict the thermal history as a function of the part shape and processing parameters. In previous work, a thermal modeling approach based on graph theory was used to predict the thermal history in LPBF parts in less-than 20% of the time required by finite element-based models with error within 10% of experimental measurements. The present work transitions toward the …
Process-Structure Relationship In The Directed Energy Deposition Of Cobalt-Chromium Alloy (Stellite 21) Coatings, Ziyad M. Smoqi, Joshua Toddy, Harold (Scott) Halliday, Jeffrey E. Shield, Prahalada K. Rao
Process-Structure Relationship In The Directed Energy Deposition Of Cobalt-Chromium Alloy (Stellite 21) Coatings, Ziyad M. Smoqi, Joshua Toddy, Harold (Scott) Halliday, Jeffrey E. Shield, Prahalada K. Rao
Department of Mechanical and Materials Engineering: Faculty Publications
In this work, we accomplished the crack-free directed energy deposition (DED) of a multi-layer Cobalt- Chromium alloy coating (Stellite 21) on Inconel 718 substrate. Stellite alloys are used as coating materials given their resistance to wear, corrosion, and high temperature. The main challenge in DED of Stellite coatings is the proclivity for crack formation during printing. The objective of this work is to characterize the effect of the input energy density and localized laser-based preheating on the characteristics of the deposited coating, namely, crack formation, microstructural evolution, dilution of the coating composition due to diffusion of iron and nickel from …
Direct Selective Laser Synthesis Of Cucrfenitial High Entropy Alloy From Elemental Powders Through Selective Laser Melting, Joni Dhar, Lazaro Lopez, Shanshan Zhang, Ben Xu, Mohammed Jasim Uddin, Jianzhi Li
Direct Selective Laser Synthesis Of Cucrfenitial High Entropy Alloy From Elemental Powders Through Selective Laser Melting, Joni Dhar, Lazaro Lopez, Shanshan Zhang, Ben Xu, Mohammed Jasim Uddin, Jianzhi Li
Manufacturing & Industrial Engineering Faculty Publications and Presentations
This study investigated the synthesis of CuCrFeNiTiAl high entropy alloy (HEA) from pure elements using selective laser melting (SLM). The objectives are to validate the feasibility of the HEA fabrication from elemental powder materials, and to examine the effect of various process conditions in SLM, such as laser power, point distance and laser exposure time, on the microstructures formed. The as-built samples under high, medium and low energy densities were characterized by X-ray diffraction (XRD), and the microstructures were observed using scanning electron microscopy (SEM). The XRD results showed that five major crystal structure phases (hexagonal, monoclinic, orthorhombic, body-centered cubic …
Microstructure Evolution And Mechanical Property Response Of Tc11 Titanium Alloy Under Electroshock Treatment, Chang Liu, Lechun Xie, Dongsheng Qian, Lin Hua, Liqiang Wang, Lai-Chang Zhang
Microstructure Evolution And Mechanical Property Response Of Tc11 Titanium Alloy Under Electroshock Treatment, Chang Liu, Lechun Xie, Dongsheng Qian, Lin Hua, Liqiang Wang, Lai-Chang Zhang
Research outputs 2014 to 2021
© 2020 The Authors This work investigated the effects of electroshock treatment (EST) on the microstructure variation and mechanical properties of TC11 alloy. The average hardness of the specimens decreased from 358 HV to 328 HV after EST of 0.04 s, then increased to 396 HV after EST of 0.06 s. After EST, the yield strength of specimen declined from 959 MPa to 797 MPa after EST of 0.04 s, and then increased to 1265 MPa after EST of 0.06 s, but the fracture strain decreased continuously. The variation in mechanical properties was closely related to the phase transition from …
Analysis Of Microstructure And Mechanical Properties Of Bismuth-Doped Sac305 Lead-Free Solder Alloy At High Temperature, Umair Ali, Hamza Khan, Muhammad Aamir, Khaled Giasin, Numan Habib, Muhammad Owais Awan
Analysis Of Microstructure And Mechanical Properties Of Bismuth-Doped Sac305 Lead-Free Solder Alloy At High Temperature, Umair Ali, Hamza Khan, Muhammad Aamir, Khaled Giasin, Numan Habib, Muhammad Owais Awan
Research outputs 2014 to 2021
SAC305 lead-free solder alloy is widely used in the electronic industry. However, the problems associated with the growth formation of intermetallic compounds need further research, especially at high temperatures. This study investigates the doping of Bismuth into SAC305 in the various compositions of 1, 2, and 3 wt.%. The microstructure in terms of intermetallic compound particles and mechanical properties was examined after thermal aging at temperatures of 100◦C and 200◦C for 60 h. The microstructure examination was observed using scanning electron microscopy, and the chemical composition of each alloy was confirmed with an energy dispersive X-ray. Tensile tests were performed …