The effects of retrogression and re-aging (RRA) treatment on intergranular corrosion (IGC), exfoliation corrosion (EXCO), stress corrosion cracking (SCC) behavior and microstructure of spray formed Al-7075 were investigated by a scanning electron microscope, a transmission electron microscope, slow strain rate test, and EXCO and IGC test. The results show that the precipitates are redissolved in the matrix of the alloy after retrogression at 200 °C for a suitable time (8 min), and the grain boundary precipitates are discrete and the obvious precipitate free zones are left at the grain boundaries. After RRA with suitable retrogressed time, thin homogeneous dispersive precipitates are separated out again in the matrix. After retrogression at 200 °C for 8 min and re-aging, the ultimate tensile strength, elongation, IGC depth, EXCO rating, and SCC index of spray formed Al-7075 are 791 MPa, 8.5%, 29.8 μm, EA, and 0.155, respectively.

When the UN Committee on Economic, Social and Cultural Rights (CESCR) released a letter in early 2012 addressing the financial and economic crises, it was long overdue. Finally, and around four and a half years after the crises began, the body responsible for monitoring those rights that had been most severely impacted had spoken. But what had been said? This article examines the alterations to the doctrine of non-retrogression that the 2012 Letter instigated. It does so by reference to the ‘Business as Usual’ and ‘accommodation’ theories of emergency response. The Letter to States is argued to have taken the Committee away from an approach to non-retrogression that treated times of normality and emergency in a similar way, and towards an approach that allows derogation-style deviations from the Covenant. This, it is argued, could have detrimental effects for the protection of economic and social rights. The difficulties in applying such an approach are considered.

In the present work, the effect of pre-ageing temperature and time variations on the mechanical properties and electrical conductivity of the Retrogression and re-aging (RRA) treated 7050 has been investigated. The results reveal that the electronic conductivity and hardness of RRA-treated samples are sensitive to the pre-ageing tempers. The RRA-treated samples with 120 °C/2 h pre-ageing +180 °C/2 h retrogression +120 °C/24 h re-ageing temper can be tailored toward a good combination of strength and elongation, while the electrical conductivity of re-ageing samples is also higher than that of 120 °C/24 h pre-ageing RRA-treated samples. With an intermediate pre-ageing temperature of 80 °C/24 h RRA-treated samples possess a higher re-aged electronic conductivity, while no significant differences can be found between hardness of 120 °C/2 h and 120 °C/24 h pre-ageing RRA-treated samples. The variation of hardness and electronic conductivity during retrogression depends on the pre-ageing tempers. For under-aged sample, the retrogression hardness appears a stage of hardness increasing followed by a further decrease in hardness results, owing to disappearance of dissolving stage of fine GP zone and η′ phase during pre-ageing.