Corrosion Behavior of Al-7wt% Si-1.5wt% Cu Severely Deformed by Equal-Channel Angular Pressing

In this study, an Al-7 wt% Si-1.5 wt% Cu alloy was subjected to severe plastic deformation (SPD) by an equal-channel angular pressing (ECAP) technique. The ECAP process was repetitively carried out up to 8 passes using a strain introduction method of route BC, at a temperature of 25 °C and a pressing rate of 0.33 mm s-1. Microstructures of the samples before and after ECAP were observed by a scanning electron microscopy (SEM). Electrochemical properties of the Al-Si-Cu alloy fabricated by ECAP have been investigated in a borate-boric acid buffer solution containing Cl¯ ions at pH 8.3 and 25 °C by potentiodynamic polarization test. Corrosion pits on the sample surface after anodic polarization were investigated by means of SEM. The anodic polarization showed that as-cast Al-Si-Cu alloy with plate-shaped Si particles has poor resistance against pitting corrosion comparing to quenched sample without ECAP. Pitting potentials of ECAPed Al-Si-Cu alloy samples were higher than that of the sample without ECAP. In the Al-Si-Cu alloy, the corrosion pits were found in the region of Si particles and the size of pits formed on the ECAPed samples became smaller than that without ECAP. It is considered that the improvement of the pitting resistance of ECAPed Al-Si-Cu alloy is due to homogenous distribution of spherical Si particles generated during ECAP process.

Variable Interval Response Rate as a Function of Prior Partial Reinforcement of a Running Response

Two groups of 8 rats were given 60 trials of 100% reward followed by 80 trials of 50% random reward in the first goal box (GB) of a double alley. The effects of non-reward in GB1 were measured in a second alley, where Ss bar-pressed on a 30-sec. VI reward schedule. Two control groups of 8 Ss received identical training except that they were never rewarded in GB1. For all Ss Alley 1 and GB1 were white, for one experimental and one control group Alley 2 was white, for the other two black. A significant frustration effect was obtained for the two experimental groups; however, this effect was not significant when compared to the bar-pressing rate of the control groups. None of the effects of brightness of Alley 2 were significant.

Effects of Bilateral Cortical Lesions on Bar-Pressing Behavior in the White Rat

It was shown that bilateral lesions in either the anterior or posterior neocortex are followed by partial disruption of a previously acquired food reinforced bar-pressing habit. The second experiment, which included a control posterior lesion group, revealed that small posterior lesions resulted in a similar performance decrement. In addition, Ss with bilateral lesions in both anterior and posterior areas exhibited approximately twice the reduction in bar-pressing rate as found in Ss with lesions in only one area. It was suggested that amount of tissue damage irrespective of the specific lesion site is perhaps the critical factor in determining postoperative rate at this stage.

Relationship between skin temperature and performance in the Java monkey

Four male Java monkeys ( Macaque iris), trained to perform a continuous avoidance task, were used in an exploratory study of diurnal skin-temperature changes and their relationship to avoidance behavior. Significant diurnal skin-temperature changes were detected, and a relationship between bar-pressing rate and skin temperature of the back was shown to exist. Submitted on December 6, 1962