Experiment_05-Heat_Treatment_of_Aluminum_Alloys_-_Age_Hardening

Experiment_05-Heat_Treatment_of_Aluminum_Alloys_-_Age_Hardening

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ME 3701, Materials of Engineering Laboratory, LSU 1 Experiment: Precipitation Hardening of Aluminum Alloys Objective The objective of this investigation is to learn how and why certain alloys (primarily Aluminum alloys) can be strengthened by Precipitation Hardening heat treatment processes. Abstract The strength and hardness of some metal alloys may be enhanced by the formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix; this must be accomplished by appropriate heat treatment. The process is called Precipitation Hardening or Age Hardening which involves three distinct steps: Solution Treatment to minimize segregation in the alloy, Quenching to create a supersaturated solid solution and Aging to facilitate the formation of coherent precipitates which strengthen the alloy by interfering with dislocation movement. Both the Natural Aging and Artificial Aging processes will be investigated by measuring the hardness of 2024 aluminum specimens at various time intervals into the aging process following the quench. Phenomena related to precipitation hardening, such as Guinier-Preston zones, overaging, coherent participates, etc., will be discussed. Background The strength and hardness of some metal alloys may be enhanced by the formation of extremely small uniformly dispersed second-phase particles within the original phase matrix in a process known as "Precipitation (or Age) Hardening". The precipitate particles act as obstacles to dislocation movement and thereby strengthen the heat-treated alloys. Many aluminum based alloys, copper-tin, certain steels, nickel-based super-alloys and titanium alloys can be strengthened by age hardening processes. In order for an alloy system to be able to be precipitation-strengthened, there must be a terminal solid solution that has a decreasing solid solubility as the temperature decreases.
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ME 3701, Materials of Engineering Laboratory, LSU 2 produced. The θ precipitates are dissolved in this step and any segregation present in the original alloy is reduced.
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This note was uploaded on 03/08/2011 for the course ME 3701 taught by Professor Moldovan during the Spring '11 term at LSU.

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Experiment_05-Heat_Treatment_of_Aluminum_Alloys_-_Age_Hardening

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