Date of Award

Spring 5-1997

Document Type

Thesis

Degree Name

Honors College

Department

Mechanical Engineering

Second Advisor

Rigers J. Hurman

Third Advisor

Beverly Wade

Abstract

The Alumniurn-Copper-Lithi arn (Al-C u-Li) alloy s are used as aero space materi als du e to thei r low den sity , hig h modulus of elasticity, good resistance to fatigue crack propagation , and excelle nt cryogenic properties. In the current experime nt, Al-Cu-L i (2 195) allo y is se lected to study the effect of the ag ing process on mechanical propertie s. The 2 195 all oy in sheet form is supplied by Lockheed-Marti n, New Orleans. The as-received 2 195 alloy sheet is solution-treated at 5 10 ° C for one hour followed by qu ench ing in wa ter. The Rockwell Hard ness as a functio n of ag ing time at 180 °C fo r the quenc hed shee t is investigated to understand the ag ing behavior of this material. The hardness of the 2 195 alloy increases rapidl y as ag ing time lasts to 4 hours, then increases slowly, and fina lly reaches a maxi mum value after approx imately 16 hours of aging. In addi tion, ten sile tests are per form ed on the 2 195 alloy sheets in the following condition s: as-rece ived, as-quenched, a nd a fter -aged. The results show tha t the afte r-aged specime n ex hibits the high est yie ld stre ngth but lowest du ctilit y co mpared wit h as- receive d and as- quenc hed specimens. The ten sil e testing results are co nsiste nt wi th the hardness tests. This demo nstrates the age hardening proce ss of Al-Cu -Li alloy.

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