GP-zones are associated with the phenomenon of age hardening, whereby room-temperature reactions continue to occur within a material through time, resulting in changing physical properties. In particular, this occurs in several aluminium series, such as the 6000 and 7000 series alloys.
Physically, GP zones are extremely fine-scaled (on the order of 3–10 nm in size) solute enriched regions of the material, which offer physical obstructions to the motion of dislocations, above that of the solid solution strengthening of the solute components. In 7075 aluminium for example, Zn–Mg clusters precede the formation of equilibrium MgZn2 precipitates.
- Guinier-Preston zone evolution in 7075 Aluminium (PDF).
- "A. Guinier - Personal Reminiscences" (PDF).
- "Microstructural Evolution and Age Hardening in Aluminium Alloys: Atom Probe Field-Ion Microscopy and Transmission Electron Microscopy Studies" (PDF).
- G.D Preston, Structure of age-hardening aluminium–copper alloys, Nature 142 (1938) 570, September 24