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A high-strength and anti-intergranular corrosion (IGC) Al-6.8Zn-2.2 Mg-Sc-Zr alloy (AS alloy) was designed, and the effects of Sc addition and Cu removal on the microstructure, mechanical properties and corrosion behavior were systematically investigated. Based on transmission electron microscopy (TEM) and Kelvin probe force microscopy (KPFM) techniques, the underlying causes of IGC and exfoliation corrosion (EXCO) of the AS alloy were investigated, and the corrosion mechanism of AS alloy was finally obtained. The AS alloy exhibits excellent mechanical properties with a tensile strength of 601 MPa in the peak-ageing condition at 120 °C, which comes from the pinning effect of Al3(Sc, Zr) dispersions. Moreover, AS alloys of T6 and T74 conditions show outstanding IGC and EXCO resistance. On the one hand, the fine, near-ellipsoidal grains in AS alloy alleviate the peeling stress caused by IGC products by blocking the formation of wedge-shaped gaps along GBs, which then bring about improved EXCO resistance. On the other hand, the removal of Cu from the traditional Al-Zn-Mg-Cu alloy avoids the segregation of Cu into GBs and thereafter reduces the fluctuations of the potential and the electron work function (EWF) across the GBs; the addition of Sc induces the high fraction of LAGBs and thus weakens the solutes' segregation at GBs, which can be beneficial for smoothing the fluctuation of corrosion potential (Ecorr) to enhance the IGC resistance.

Soil organic carbon (SOC) is heterogeneous, consisting of fractions with differing turnover rates. Climate, vegetation, and soil properties can all affect the characteristics of these different soil carbon fractions. However, there has been little investigation into the interactive effects of biotic and abiotic drivers on a large spatial scale. In this study, we utilized data from the international soil radiocarbon database (ISRaD) to investigate the radiocarbon abundance (an indicator of carbon persistence) in soil fractions from several different biomes. Bulk SOC was categorized into three fractions according to the density fractionation method: a free light fraction (fLF), an occluded light fraction (oLF) and a heavy fraction (HF). In addition to the impacts of significant factors such as depth and climate, interactive effects between soil fractions and environmental factors on radiocarbon abundance were prevalent. Specifically, there were significant interactions between climate, vegetation types, soil properties, and soil fractions affecting Δ14C levels. The difference in Δ14C of the shallow depth fractions was significant in the temperate forest, and was not significant in the boreal and tropical forests. The interactive effect between mean annual temperature (MAT) and mean annual precipitation (MAP) on Δ14C was significant in the shallower depth (i.e., 0–30 cm and 30–60 cm) of the oLF and in the deeper soils (i.e., 30–60 cm and 60–100 cm) of the HF. Soil properties also interact with soil fractions in determining Δ14C. After accounting for depth effect, oxalate-extractable aluminum (Alo) accounted for 63.5% of the remaining Δ14C variation in the fLF and accounted for 35.9% of the remaining Δ14C variation in the oLF. Rather than Alo, cation exchange capacity (CEC) accounted for 46.1% of the remaining Δ14C variation in the HF. These findings suggest that the way the interactions between climate, vegetation, and soil properties affect soil carbon persistence at various fractional depths is critical for the accurate prediction of soil carbon dynamics.

The quench-induced precipitation and subsequent aging response in 2A97 aluminum alloy was investigated based on the systematic microstructure characterization. Specifically, the influence on precipitation from grain structure was examined. The results indicated the evident influence from the cooling rate of the quenching process. Precipitation of T1 and δ′ phase can hardly occur in the specimen exposed to water quenching while become noticeable in the case of air cooling. The yield strength of 2A97-T6 alloy de-graded by 234 MPa along with a comparable elongation when water quenching was replaced by air cooling. Sub-grains exhibited a much higher sensitivity to the precipitation during quenching. The presence of dislocations in sub-grains promoted the quench-induced precipitation by acting as nucleation sites and enhancing the diffusion of the solute. A quenching rate of 3 °C/s is tolerable for recrystallized grains in 2A97 Al alloy but is inadequate for sub-grains to inhibit precipitation. The study fosters the feasibility of alleviating quench-induced precipitation through cultivating the recrystallization structure in highly alloyed Al–Cu–Li alloys.