The effects of additional elements on the galvanic anode properties of aluminum and its alloys were examined.
The anodic behaviors were determined under the following experimental conditions:
Anodic current density……1mA/cm²
electrolyte……artificial sea water at room temperature
perio……168hr.
Throughout the test, the anode potential was measured at regular intervals and the final weight loss of the anode was also measured.
The results obtained were as follows.
(1) For pure aluminum (99.7-99.8%), the addition of Zn, Sn, In, or Hg improved anode performance. Hg was the most effective among them.
(2) For Al-3% Zn alloy, Al-0.1% Sn alloy, and Al-0.1%, In alloy, the addition of Ti or Zn was comparatively effective, but other additional elements were no effective, except Zn, Sn, In, and Hg.
(3) For Al-Mg alloys, Al-Zn alloys, and Al-Sn alloys, the addition of Hg was very effective.
The alloys containing 0.05% of Hg showed anode potential of-1.00_--1.05V and current efficiency of 90-95%. However, the corrosion of Al-Hg alloys was not uniform.

View full abstract

The solid solubility limit of Fe, Ni, or Co in aluminum is extremely low, but these elements have very fatal effects on the physical and chemical effects of aluminum.
The grain-boundary segregation in aluminum specimens containing 0.006-0.04 at % of Fe, Ni, or Co was studied by using low-frequency internal friction and Instron tension tester.
The specimens were water-quenched after being preheated at 620 or 630°C, and then, the grain-boundary relaxation and work hardening at 90°K were measured.
The results obtained were as follows.
1. Fe, Ni, or Co greatly lowered the grain-boundary peak and high-temperature background of internal friction. The above facts expressed that these elements were segregated near grain-boundaries to inhibit boundary sliding or migration.
2. Fe, Ni, or Co greatly improved the work hardeness of 90°K. The maximum value of hardness index was observed at about 0.013 at % of Co in Al-Co system or at about 0.032% at % of Fe in Al-Fe system. The above behavior was explained by either the increase in the back stress for the propagation of dislocation or the rapid multiplication of dislocation near the segregated grain-boundary.
It is concluded that most of Fe, Ni, or Co atoms in aluminum are segregated near grain-boundaries or sub-boundaries even at as low as 620°C. The boundary segregation is more remarkable when the temperature is lower.
Substitutional solid solubility limits of these elements in aluminum lattice will be much lower than the values reported in the past.

View full abstract

The effects of the addition of Zinc (0.3-2%) on the mechanical properties of Al-Si(5%)-Mg(0.3-1.0%) alloys were investigated and the following results were obtained.
(1) Al-Si(5%)-Mg(0.8%)-Zn(1-2%) alloy was solution heat treated at 550°C for 3hr. and tempered at 150°C for 30hr. Then, the tensile strength was 37kg/mm² in sand casting or 39kg/mm² in metallic mold casting.
(2) Al-Si(5%)-Mg(0.8%)-Zn(1-2%) alloy was solution heat treated at 550°C for 10hr. and tempered at 150°C for 20hr. Then, the tensile strength was 40kg/mm² in metallic mold casting.

View full abstract

The effects of the addition of cerium on workability of magnesium were studied. The workability of magnesium alloys having various contents of cerium was evaluated by the total elongation of test pieces in tension test and by the working limit of plates in cold rolling, at which the occurrence of cracks appeared on the side faces of the plates.
The alloy containing 0.2wt.% of Ce exhibited the largest elongation in tension test and also the highest working limit in cold rolling. The workability of magnesium was generally improved by the addition of cerium, the effects and would be due to the occurrence of deformation bands caused by compressive strain. The results showed that in case of pure magnesium a few number of deformation bands were observed being concentrated in limited regions; while, in alloys containing cerium the deformation bands were uniformly distributed throughout the pieces. It was also observed that the deformation bands started to from at the regions near grain boundaries and gradually spread into the grains.
At the final stage of deformation, the formation of cracks was associated with deformation bands, and then they developed along the bands.

View full abstract