ALUMINUM ALLOY TWO-STEP AGING METHOD AND ARTICLE

摘要

A method for thermally treating an article made from an aluminum alloy having a first temperature at which solute atoms cluster to yield nuclei for the formation and growth of strengthening precipitates, and a second higher temperature at which the strengthening precipitates dissolve. The method comprises: heating the article to allow substantially all soluble alloy components to enter into solution; rapidly cooling the article in a quenching medium; and precipitation hardening the article by aging at or below the first temperature for a few hours to several months; then aging above the first temperature and below the second temperature until desired strength is achieved. A method for imparting improved combinations of strength and fracture toughness to a solution heat treated article which includes an aluminum-lithium alloy is also disclosed. This method comprises aging the article at one or more temperatures at or below a first temperature of about 93.degree.C (200.degree.F) for a few hours to several months; and further aging the article at one or more temperatures above the first temperature and below a second temperature of about 219.degree.C (425.degree.F) for at least about 30 minutes.