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Selected results of investigations focused on the changes to some mechanical properties of palladium and several palladium-based alloys caused by exposure to hydrogen have been collected and presented. The findings indicate that the mechanical properties of pure palladium are highly susceptible to alteration upon exposure to hydrogen. In the cases of alloying palladium with silver and copper, the alloys, as compared to palladium, appear to resist changes to mechanical properties. In the case of alloying palladium with manganese, the interesting order–disorder phenomenon plays an important role on the effects of hydrogen exposure on their mechanical properties. [ABSTRACT FROM AUTHOR]

The yield strength, ultimate strength, and elongation/ductility properties of a series of palladium–copper alloys were characterized as a function of the temperature at which each alloy underwent absorption and desorption of hydrogen. The alloys studied ranged in copper content from 5 weight percent copper to 25 wt.% copper. Compared to alloy specimens that had been well-annealed in a vacuum and never exposed to hydrogen, alloys with copper content up to 15 wt.% showed strengthening and loss of ductility due to hydrogen exposure. In these alloys, it was found that the degree of strengthening and loss of ductility was dependent on the hydrogen exposure temperature, though this dependence decreased as the copper content of the alloy increased. For alloys with copper contents greater than 15 wt.%, hydrogen exposure had no discernible effect on the strength and ductility properties compared to the vacuum-annealed alloys, over the entire temperature range studied. [ABSTRACT FROM AUTHOR]

Strength, hardness, and ductility characteristics were determined for a series of palladiumcopper alloys that compositionally vary from 5 to 25 weight percent copper. Alloy specimens subjected to vacuum annealing showed clear evidence of solid solution strengthening. These specimens showed, as a function of increasing copper content, increased yield strength, ultimate strength, and Vickers microhardness, while their ductility was little affected by compositional differences. Annealed alloy specimens subsequently subjected to exposure to hydrogen at 323 K and PH2 = 1 atm showed evidence of hydrogen embrittlement up to a composition of ~15 wt. % Cu. The magnitude of the hydrogen embrittlement decreased with increasing copper content in the alloy. [ABSTRACT FROM AUTHOR]

The influence of hydrogen as an agent to accelerate the thermal recovery of cold-worked palladium has been investigated. The techniques used to characterize the effects of hydrogen on the thermal recovery of palladium were hydrogen solubility and mechanical property measurements. Results show that the presence of modest amounts of hydrogen during annealing of cold-worked palladium does enhance the degree of thermal recovery, with a direct correlation between the amount of hydrogen during annealing and the degree of recovery. The results indicate that the damage resulting from cold-working palladium can be more effectively and efficiently reversed by suitable heat treatments in the presence of appropriate amounts of hydrogen, as compared to heat treatment in vacuum. The somewhat novel technique of using changes in the hydrogen solubility of palladium as an indicator of thermal recovery has been validated and complements the more traditional technique of mechanical property measurements. [ABSTRACT FROM AUTHOR]

The effects on the strength, hardness, and ductility of a series of well-annealed palladium-silver alloys due to hydrogen exposure were investigated at various temperatures. The results indicate that the temperature at which hydrogen exposure occurs can have a significant effect on the degree to which these mechanical properties are altered. At relatively low temperatures, it was found that the strength and hardness of the alloy are increased, while ductility is decreased upon hydrogen exposure. In alloys where such changes are observed, the magnitude of these changes was found to diminish as the silver content increases. Above a certain hydrogen exposure temperature--the value of which decreases with increasing silver content--the strength, hardness, and ductility of the alloy show no significant changes as a result of hydrogen exposure. [ABSTRACT FROM AUTHOR]

A study into the effects of hydrogen absorption followed by complete desorption by the alloy palladium–silver (25wt.%) has been carried out over the temperature range of 303–473K. The results indicate that at all temperatures studied the strength, hardness and ductility show no significant changes as a result of exposure to hydrogen, as compared to the well-annealed alloy that had not been exposed to hydrogen. [Copyright &y& Elsevier]

Abstract: A systematic study of the tensile strength, hardness, and ductility of palladium has been performed on foil specimens that have undergone hydrogen absorption and desorption under a variety of conditions. The experimental parameters under control in the various hydrogen treatments were: (i) the amount of hydrogen absorbed, (ii) the isotope of hydrogen (protium versus deuterium) absorbed, (iii) the number of hydrogen absorption/desorption cycles, and (iv) the hydrogen absorption/desorption temperature. In all instances hydrogen absorption/desorption cycling significantly alters the tensile strength, hardness, and ductility of well-annealed palladium. The results show that, in general, the strength and hardness of palladium increases as a result of hydrogen cycling while the ductility decreases. The extent of the respective increases and decreases has been found to differ depending on the parameter being varied. The most sensitive parameter was found to be the amount of hydrogen absorbed during cycling. [Copyright &y& Elsevier]

Changes in the mechanical properties of palladium that has undergone a cycle of hydride formation and decomposition in the temperature range 323–623K have been characterized. The results show that at all temperatures studied cycling increases the strength and hardness of palladium while decreasing ductility, compared to well-annealed palladium. The extent of the changes in mechanical properties has been found to be essentially independent of cycling temperature up to 473K and dependent on cycling temperature above 473K. [Copyright &y& Elsevier]