Testing Natural Aging Effect on Properties of 6066 & 6063 Alloys Using Vickers Hardness and Positron Annihilation Lifetime Techniques

Abstract

The aim of this work was to produce a high strength 6xxx series Aluminum alloy by adjusting the processing conditions, namely solutionizing and natural aging. It consists of heating the alloy to a temperature at which the soluble constituents will form a homogeneous mass by solid diffusion, holding the mass at that temperature until diffusion takes place, then quenching the alloy rapidly to retain the homogeneous condition. In the quenched condition, heat-treated alloys are supersaturated solid solutions that are comparatively soft and workable, and unstable, depending on composition. At room temperature, the alloying constituents of some alloys tend to precipitate from the solution spontaneously, causing the metal to harden in about four days. This is called natural aging. The mechanical characterization of heat treatable 6xxx (Al-Mg-Si-Cu based) 6066, 6063 wrought aluminum alloys was studied. Their effects were investigated in terms of microstructure using positron annihilation lifetime technique and mechanical properties by hardness measurements. The hardness is the Resistance of material to plastic deformation, which gives it the ability to resist deformed when a load is applied. The greater the hardness of the material, the greater resistance it has to deformation. Hardness measurement can be defined as macro-, micro- or nano- scale according to the forces applied and displacements obtained. Micro hardness is the hardness of a material as determined by forcing an indenter such as a Vickers indenter into the surface of the material under 15 to 1000 gf load; usually, the indentations are so small that they must be measured with a microscope. During this work we are monitoring the effect of natural aging on the properties of positron lifetime and Vickers hardness parameters. The Vickers hardness of 6066 alloy has a maximum value(80) after (10)days of quenching at 530 which is the solution temperature of this alloy .the hardness of 6063 alloy has a maximum value (40) after (14)days of quenching at 520 which is the solution temperature of this alloy. The hardness which is conformed to the references.