Form This specification covers an aluminum-lithium alloy in the form of extruded profiles 0.040 to 1.000 inch@ incl in thickness. Application These extrusions have been used typically for machined parts requiring dimensional stability during machining processes@ and high strength@ but usage is not limited to such applications. Certain processing procedures may cause this product to become susceptible to stress-corrosion cracking; ARP823 recommends practices to minimize such conditions.