Nacer Zazi

Thermomechanical treatments effect on corrosion behaviour of aluminium-magnesium alloy AA5083-H321

In this paper the process of the corrosion of the alloy 5083-H321 has been studied in 3% weight NaCl solution. We were interested in the effect of change in the physical state and chemical composition of the intermetallic particles on corrosion behavior of aluminum 5083-H321 alloy having undergone an annealing of 1h 30 min at 420°C, and having undergone the same annealing followed by various types of thermo-mechanical treatments. The results obtained show that the density of the intermetallic particles increases by 10 times and micropores are formed after the deformation by cold rolling. The distribution law of intermetallic particles changes after cold rolling. The morphology of corrosion changes also. The introduction of an intermediate annealing process during cold rolling of 1h at 250°C causes a recrystallization in the alloy but does not bring change on the corrosion morphology.

Stress in Aluminium Alloys Measured Using Göbel Mirror as a Primary Beam Optics of X-Ray Diffractometer

Grazing incidence geometry, called MGID-sin2y, was applied to measure surface stresses in very thin layers (depth of a few mm) of Al-Mg alloy samples subjected to different thermal and mechanical treatments. The Göbel mirror was used to parallelize the incident X-ray beam. Perfect collimation of the beam significantly increases accuracy of determined peak position and consequently allows to measure low stresses in surface layers.

Investigation of nickel deposition onto section and central longitudinal surfaces of AA1370 aluminum electrical wire with and without a weak permanent magnetic field

In this work a special regard is given to the morphology of the nickel deposited layers, onto AA1370 aluminum section and central longitudinal surfaces, with and without a weak magnetic field oriented in parallel and perpendicular to the coated surface in modified Watt bath. The obtained results show the formation of honeycomb structure nickel deposits for samples treated with weak parallel oriented field under approximately 0.3 A/cm2, and partial dendritic structure nickel deposit for samples treated with weak perpendicular oriented magnetic field, the perimeter deposits with and without magnetic field is different to the deposits in the remain surface. We attributed the defect of nickel deposits on the surfaces with and without magnetic field to the distribution of the intermetallics particles and we attributed the honeycomb structure to the escapement of hydrogen and oxygen.

Stress Measurements in Polished Al-Mg Alloy and CrN Coating Using Multireflection Grazing Incidence Method

The multi-reflection grazing incidence X-ray diffrection was used to determine residual stress gradient in the mechanically polished Al-Mg alloy and CrN coating. Also, the root mean square values of the third order lattice strain was determined using Wiliamson-Hall method. The results obtained for Al-Mg alloy show that the stress field in the surface layer as well as the microstructure (density of dislocation) depend strongly on the sample preparation. A very high residual compressive stress, which does not change significantly with depth, was measured in the CrN coating. Moreover, a large value of the measured third order strains in the coating was found.

Sulfuric Containing Sugar Bath and Permanent Weak Magnetic Field Effect during Anodizing AlCu 6 Si Alloy Sheet Surfaces

Rolling and perpendicular to rolling surfaces of AlCu6Si aluminum sheet have been anodized at 27 ± 1°C in 20 wt % sulfuric acid containing an additive of white sugar powder with and without permanent weak magnetic field. After one hour of anodizing, some hillocks-shaped micropores are developed and craters are formed in the oxide layers. The micropores obtained in rolling faces are often smaller than those obtained on other faces. Sulfuric anodizing at 21 V causes the formation of combined micropore-nanopore structures in rolling surface. It demonstrated that sugar additive increases the density of micropores in spherical shape in rolling surface and the increasing of sugar concentration changes the pores to hillocks form. In addition, the application of weak magnetic field induces homogeneous repartition of micropores.

Corrosion behavior on the different zones of AA2014 welded aluminum alloy by AA5554 filler aluminum alloy with TIG process: Before and after solution heat treatments followed by ageing

In this work, we have studied the effects of solution heat treatment followed by ageing on the corrosion behavior of AA2014 aluminum alloy welded by AA5554 aluminum alloy. Two samples are then analyzed, in the first case the solution heat treatment is followed by quenching and natural ageing of 90 days (sample 1), and in the second one, the solution heat treatment is followed by quenching and artificial ageing of twelve hours at 190°C (sample 2). The principal observations can be summarized as: evaporation of magnesium in fusion zone, and diffusion of magnesium and copper from the heat affected zone to the fusion zone were identified. Solution heat treatment, quenching and 90 days of natural ageing leads to a uniform corrosion in the heat affected zone and in the fusion one, when the material is immersed for ten seconds in Keller reagent solution. After immersion in 0.3% NaCl chloride solution, and after solution treatment and quenching, we observed that applied artificial ageing at 190°C causes localized corrosion surrounding precipitates and then develops uniform corrosion in all zones, particularly in the fusion one. Finally, it is noted that the surface of different zones became nobler after applying solution heat treatment followed by natural ageing.

Dissolution of Ag/AgCl Reference Electrode and Deposition of Silver Onto the Surface of 5083 H321 Aluminum Alloy, During Corrosion in 3 wt % NaCl Solution at Rest Potential

The dissolution of Ag/AgCl reference electrode and deposition of silver onto 5083-H321 aluminum alloy in 3 wt % NaCl solution have been observed. This result was obtained after one month of AA5083-H321 aluminum alloy corrosion at 25°C and rest potential in a classic cell of three electrodes, the reference electrode is silver/silver chloride bar and the auxiliary electrode is platinum wire. We have observed silver deposition onto three samples prepared from the same sheet. The sample 0 has undergone during the industrial manufacturing process a cold rolling followed by an industrial stabilization (in such industrial process the annealing temperature is maintained between 50 and 200°C), and undergone an annealing at 420°C during 90 minutes in laboratory. The Sample 1 and 2 have undergone a cold rolling of 46% and 92% reduction, respectively.