Materials and Design 24 (2003) 151–155 0261-3069/03/$ - see front matter  2003 Elsevier Science Ltd. All rights reserved. PII: S0261-3069 Ž 02 . 00106-1 Quenched-in lattice defects in pure aluminium (99.999%) Abdul Faheem Khan *, Anwar Manzoor Rana , M. Iqbal Ansari a, a b Department of Physics Materials Science, Bahauddin Zakariya University, Multan 60800, Pakistan a Department of Physics, College of Science, King Saud University, Riyadh 11451, Saudi Arabia b Received 24 July 2002; accepted 23 October 2002 Abstract Prepared specimens of pure aluminium (99.999%) in the form of thin sheets of 100-mm thickness were used for electrical resistivity measurements. Samples were quenched after heating at different temperatures ranging from 373 to 723 K for 30 min. Samples were also annealed for a constant time of 30 min at different temperatures (373–673 K). It was observed that resistivity of pure aluminium increases with increase in temperature. The effect of annealing and quenching on electrical resistivity had also been observed. It was found that the room temperature resistivity increases with increase in quenching temperature but decreases after subsequent annealing at various temperatures. Increase in resistivity after quenching was found to be due to creation of defects and imperfections such as vacancies and dislocations etc. Decrease in resistivity after annealing can be attributed to recovery and recrystallization processes.  2003 Elsevier Science Ltd. All rights reserved. Keywords: Pure aluminium; Lattice defects; Quenched-in 1. Introduction The mechanical properties such as flow stress, hard- ness and ductility of metals and alloys recover mono- tonically towards the values characteristic of the fully annealed stage during the process. Obviously, the cells developed during deformation prior to the annealing process, grow in size during the recovery stage and presumably set the stage for eventual recrystallization events in metals or alloys w1,2x. So the kinetics of recovery in terms of sub-grain growth becomes a very critical area, which may need a better understanding in order to control the industrially important process of annealing. Electrical resistivity (a specific characteristic of met- als yalloys) data can be useful to understand various phenomena in metals and alloys. For example, the resistivity measurements provide an easy and an inex- pensive method for study of phase transitions with change of temperature in crystalline and amorphous metals yalloys w3–7x. Similarly, residual resistivity meas- urement is one of the most simple and sensitive methods *Corresponding author. E-mail address: faheem_khan_1977@yahoo.com (A.F. Khan). for studying impurities, defects and other structural changes w8x. When the specimen is heated up to certain suitable temperature, atoms in the specimen starts oscillating within certain limits about their mean position. If the specimen is quenched, the atoms freeze at their present position, therefore, defects and vacancies are produced in the specimen and if temperature is low enough, the equilibrium concentration of vacancies will be frozen in the sample w11x. The rapid quenching of a close-packed metal from a high temperature should ‘freeze in’ large numbers of lattice vacancies (single and possibly pairs) which are in thermal equilibrium at high temperatures. In close packed metals, vacancies are favored as the defects rather than interstitial atoms, because they require as much energy as interstitials w12–14x. The relative concentration of vacancies present after quench- ing may be obtained by measuring the increase in electrical resistivity, which the vacancies produce. The changes in the quenched material are so fast that it is in a state of strain that may cause surface or internal cracks. The strains set up in a quenching process are relieved completely during annealing w15x. Annealing of a specimen may affect either density of current carriers or their mobility. In metals and alloys