The 7XXX series alloys are heat-treatable Al-Zn-Mg or Al-Zn-Mg-Cu alloys. They develop their strength by solution heat treatment followed by ageing. In contrast to the 5XXX series alloys, the 7XXX series alloys do not respond favourably to cold work, because they are strengthened almost exclusively by GP zone formation and precipitates which nucleate from the GP zones. Introducing many new disl...

Ageing is associated with a decrease in the ability of cells to cope with environmental challenges. This is due partly to the attenuation of a primordial stress response, the so-called heat shock (HS) response, which induces the expression of heat shock proteins (HSPs), composed of chaperones and proteases. The attenuation of the HS response during ageing may be responsible for the accumulation...

This research was carried out to study the effect of ageing on antioxidant and biochemical changes of wheat (Triticum aestivum L.) seeds. The experiment laid out in completely randomized design (CRD) with four replications in Islamic Azad University, Boroujerd Branch, Boroujerd, Iran in 2015. The seeds of wheat (cv Sardari) were harvested at maturity and ageing treatments were done at 43° C wit...

Precipitation hardening, because it involves the hardening of the material over a prolonged time, is also called age hardening, or ageing. By the appropriate heat treatment of precipitation hardening, the strength or hardness of some heat-treatable aluminium alloys can be enhanced by the formation of nano-meter sized second-phase precipitated particles within the original phase matrix. The fine...

The effect of deep cryogenic treatment (DCT) on the artificial ageing kinetics a SiC particles reinforced aluminum alloy composite (SiCp-Al) is experimentally studied in this paper. evolutions both macro-properties (i.e., yield strength and ultimate tensile strength) microstructures (precipitates) have been investigated by set hardness tests, microstructural observations (scanning electron micr...

Nano-particle hydroxyapatite (HA) rods, were rapidly synthesised using a three pump continuous hydrothermal process (using a water feed at up to 400 degrees C and at 24 MPa): the product was obtained as a highly crystalline and phase pure material, without the need for an ageing step or subsequent heat treatment.

Maraging steels gain many of their beneficial properties from heat treatments which induce the precipitation of intermetallic compounds. We consider here a two-stage heat-treatment, first involving austenitisation, followed by quenching to produce martensite and then an ageing treatment at a lower temperature to precipitation harden the martensite of a maraging steel. It is shown that with a su...

The influence of artificial ageing on bonded heat-treated spruce lamellas was investigated. Heat-treated with different degrees thermal modification were PVAc and MUF then exposed to 500 weathering cycles, combined rain, UV IR radiation. colour change the surface, weight change, delamination joints adhesive bond strength measured. Artificial caused cracking reduced both adhesives. results show ...

An experimental study is presented on the effect of microstructural change on the Portevin-Le Chatelier effect behaviour of Al-2.5%Mg alloy. Tensile tests are performed on the as received and heat treated (at 400 oC for 16 hours) samples for a wide range of strain rates. The serrations observed in the stress-time curve are investigated from statistical analysis point of view. Microstructures of...

Increased adoption of additively manufactured superalloys has led to the consideration revised heat treatment approaches for these materials. The rapid cooling during additive manufacturing processes been seen suppress gamma prime (γ′) precipitation, which raised possibilities omitting high-temperature solution step that usually precedes ageing alloys. In this work, as-built microstructure a hi...