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A feasibility study on the effect of an Al-C master alloy on the microstructure and mechanical properties of the B319 cast aluminum alloy

University of British Columbia

Aluminum alloys have a high strength to weight ratio (x2 of most steel alloys) and are therefore excellent candidates for use in dynamic weight-sensitive designs (e.g. the aerospace, marine, and automotive industries). The B319 aluminum alloy is currently used in complex cast automotive parts, such as the engine block or cylinder head, due to its excellent castability and heat treatability. Improvements to the B319 alloy’s strength and casting characteristics can lead to further weight reduction of parts, which translates to improved vehicle efficiency, lower cost, and reduced green house gas emissions. Grain refinement is a method of increasing material properties without significantly altering the parent alloy. However, production of well dispersed and consistent master alloys to achieve effective grain refinement remains an industrial challenge. This research investigated the effectiveness of a novel Aluminum(Al)-Carbon(C) master alloy for grain refinement of the B319 alloy. The master alloys were synthesized via the spark plasma sintering (SPS) powder metallurgy process, and subsequently characterized by microstructural analysis. Casting experiments were then carried out with the B319 alloy, and the resultant as- cast materials were analyzed. The results showed that a well dispersed Al-C master alloy could be synthesized by SPS, with carbon black powder equally distributed at the aluminum particle boundaries. The carbon was seen to diffuse at the Al-C interface at sintering temperatures of <500°C. Low concentration (1wt% C) and high concentration (2wt% C) master alloys were added to B319 alloy castings at 0.03wt% total C content. Thermal analysis and microscopy showed no change in the solidification reactions, solidification profiles, or microstructure of the B319 alloy after master alloy addition. Grain size evaluation showed a maximum grain size decrease of 17% when a high concentration master alloy was used. Mechanical and fluidity tests further showed either no improvement or marginal property decreases associated with Al-C addition.

Text

2019-05-03

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/70048

Mechanical Engineering

University of British Columbia

UBCO

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