Aluminium Lithium alloys with higher strength, greater stiffness, and lighter weight is considered as an emerging and an attractive aerospace material. Each percent of lithium, up to 4 % reduces the overall weight by 3% and increases stiffness by 6%. Alloys have already been developed that have 8 to 10 % lower density, 15% to 20% greater stiffness, strengths comparable to those of existing alloys, and good resistance to fatigue crack propagation, but fracture toughness, ductility, and stress corrosion resistance are usually poorer than for conventional alloys. They are highly machinable, can be welded, and are readily adaptable to forming by forging or extrusion. Some sheet material can be even fabricated by superplastic forming. Thus, significant weight savings can be achieved without the major overhaul of manufacturing equipment that would be associated with a switch to advanced composites. Aluminium Manganese alloys contains 1.2% Manganese produces a moderately strong non heat treatable aluminium alloy. The manganese addition strengthens the aluminium by solid solution strengthening and by a fine dispersion of precipitates. Further, strength is increased by increasing the magnesium addition up to about 1 percent. These alloys are used for general purposes where moderate strength and good workability are required. These alloys are used to manufacture cooking utensils, building products such as siding, and gutters.
Steel is strong in compression and tension. It is normally used to reinforce concrete structures as concrete has a higher compressive strength then steel, but steel has a much higher tensile strength in comparison.
