Effect of Minor Yttrium Additions on the Mechanical Properties of 8090 Al-Li Alloy at Ambient and Cryogenic Temperatures
The effects of minor Y additions to the 8090 Al-Li alloy were investigated in the temperature range 293 to 77 K. Results of tensile tests of smooth and notched specimens and Charpy impact toughness tests showed that Y improved the ultimate tensile strength, yield strength, and ductility of the 8090 Al-Li alloy at low temperatures. With decreasing temperature, the elongation of the 8090 Al-Li alloy decreased slightly, but it increased in the Y-containing alloy. At 77 K, elongation of the Y-containing alloy was 46% more than that of the alloy without the Y addition. The addition of Y improved the notched tensile strength and Charpy impact toughness but had little effect on the notch sensitivity. A possible mechanism to explain the phenomena is discussed. The improvements in mechanical properties are due mainly to the more uniform distribution of the S′ (Al2CuMg) phase resulting from the Y addition.
KeywordsUltimate Tensile Strength Planar Slip Charpy Impact Notch Sensitivity Charpy Impact Toughness
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