Abstract: A heat treatable 7000 series aluminum alloy has a micro-structure with a crystal grain size of 45 .mu.m or less and an aspect ratio (longitudinal/long transverse ratio of crystal grain) of preferably 4 or less, whereby its corrosion resistance is improved outstandingly by applying a solution heat treatment and hardening and subsequently, applying an aging treatment at 100 to 145.degree. C. for 5 to 50 hr, a reversion treatment at 140 to 195.degree. C. for 0.5 to 30 hr. and a re-aging treatment at 100 to 145.degree. C. for 5 to 50 hr. to thereby make an electroconductivity to 38-40 IACS %, and render the micro-structure so as to have a minimum distance for the .eta. phase on the crystal grain boundary of 20 nm or more and a maximum size for the .eta.' phase in the crystal grain of 20 nm or less.

Abstract: There is provided Al alloys which have improved and excellent fracture toughness and fatigue characteristic and improved formability, and which can be suitably used for transportation machines, such as aircraft, railway vehicles, general mechanical parts and the like. The Al alloy contains 1 to 8% (% by weight, the same is true for the following) of Cu, containing one or more selected from a group comprising 0.4 to 0.8% of Mn, 0.15 to 0.3% of Cr, 0.05 to 0.1% of Zr and 0.1 to 2.5% of Mg, Fe and Si each being less than 0.1%, a distance between constituents being more than 85 .mu.m, and having a micro-structure fulfilling at least one of the following (a) to (c):(a) the size of Al--Mn dispersoids is 4000 .ANG. or more,(b) the size of Al--Cr dispersoids is 1000 .ANG. or more, and(c) the size of Al--Zr dispersoids is 300 .ANG. or more.

Abstract: An aluminium alloy with superior thermal neutron absorptivity contains 0.2-30 wt. % of Gd. An aluminium alloy for an wrought material with high-temperature strength contains 0.2-20 wt. % of Gd and 0.5-6 wt. % of Mg. An aluminium alloy for casting contains 0.2-10 wt. % of Gd and 6-12 wt. % of Si.

Abstract: Sheets of high strength superplastic Al--Zn--Mg alloys or Al--Cu alloys which having a maximum grain size below 30 .mu.m on average are described. These alloy sheets are obtained by a method which is characterized by keeping a homogenized and hot worked ingot of the alloy at two different temperatures for sufficient times whereby a fine grain structure is formed in the alloy to impart superplasticity to the alloy.