Date of Award

Fall 2021

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Mechanical, Automotive, and Materials Engineering

First Advisor

H. Wu

Second Advisor

V. Stoilov

Third Advisor

X. Nie

Keywords

Chemical composition, Metal alloy, High strength, Electrical conductivities

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Mechanical strengths and electrical conductivity are the very important engineering properties of lightweight metallic materials used in the automotive industry, especially for battery-powered electric vehicles (BEV). However, the main issue is that high strength and high electrical conductivity are mutually exclusive due to physical nature of these properties. The aim of this study is to develop new cast aluminum alloys for the production of rotor bar in the rotor with high as-cast strength and electrical conductivity. A design of experiment (DOE) technique, Taguchi method, was used to develop high as-cast strength and electrical conductivity alloys with various element addition of Si, Cu, Ni and Sr. The optimal combination of chemical composition for maximizing the ultimate tensile strength (UTS), electrical conductivity (σ) and yield strength (YS) was 6 wt.% Si, 3 wt.% Cu, 0.03 wt.% Sr and 0.5 wt.% Ni. The alloy with the optimal composition had an averaged UTS of 247.58 MPa, an averaged electrical conductivity is 38.01 %IACS, and an averaged yield strength of 143.47 MPa. In comparison to those of the alloy free of Sr and Ni, the additions of 0.03 wt.% Sr and 0.5 wt.% Ni in the Al-6Si-3Cu alloy significantly improved the ultimate tensile strength, yield strength and electrical conductivity. This was because the addition of Ni element, as a transition element, collaborated with Cu to form intermetallic Al-Cu-Ni phases for dispersion strengthening. Also, the modification of the Si morphology from micron needles to nano particles by the Sr addition enhanced both the strengths and electrical conductivity of the developed alloy.

Share

COinS