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Kozakevich, Jordan Roger

University of British Columbia

With the annual increasing effects of climate change becoming more evident industries are looking inward to do their part and help minimize global warming. Over the past decade, the transportation industry has invested significantly in new, innovative solutions to help reduce its carbon footprint. A significant area the automotive industry is currently driving is the development of new, lightweight metals that can withstand increased elevated temperatures. Currently, spark ignition internal combustion engine operates between 200 to 225 °C. To increase the fuel efficiency of these engines, there needs to be an increase in work output. The result of increased work output is a proportional increase in operating temperature. Current aluminum alloys used for light weighting components cannot withstand these temperature increases. Therefore, the transportation industry needs new alloys with this thermal capability. A foundation has been laid, and a strong case has been made for the Aluminum-cerium alloying system to take over elevated temperature applications in the automotive industry. These alloys boast superior thermal stable intermetallics as compared to the alloys containing Si precipitates such as Mg₂Si and the Si eutectic phase. This enhanced thermal stability results in the capability of retaining a significant portion of their mechanical properties at a temperature above 225 °C. Thus, this research thesis aimed to develop and characterize a novel Al-Ce-Ni-Mn tailored for elevated temperature tensile properties. The final composition of the alloy was Al-11.3Ce-3.2Ni-1.2Mn (wt.%). The alloy exhibited superior yield strength (YS) mechanical retention of up to 97 % and ultimate tensile strength (UTS) retention of up to 83 % at 250 °C. Additionally, a characterization of the alloy’s interplay between cooling rate, microstructure, and mechanical properties was done in the range of 0.18 to 8.42 °C/s. Five phases were found in the alloy’s complex microstructure: α-Al, Al₂₃Ce₄Ni₆, Al₁₁Ce₃, Al₁₀CeMn₂, and Al₂₀CeMn₂ (at.%). A cooling rate of 0.63 °C/ resulted in the greatest room temperature YS and UTS at 81 and 131 MPa, respectively. A cooling rate of 1.36 °C/s resulted in the greatest 250 °C YS and UTS at 64 and 104 MPa, respectively.

Text

2022-12-16

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83442

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/