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The corrosion behavior of unaged and thermally aged Ni–25Cr–10Fe–3Si–xMo (x = 0, 3 wt%) alloys was studied beneath KCl–ZnCl2 deposits at 650°C. The results indicated that the addition of Mo promoted the formation of a continuous Si‐rich protective layer and improved the corrosion performance of the unaged Ni–25Cr–10Fe–3Si–xMo alloys. The precipitates formed after long‐term aging greatly affect the corrosion resistance of the thermally aged alloys. The M23C6 along the grain boundaries is beneficial to improve corrosion resistance, however, the dispersed Laves phase and Sigma deteriorate corrosion resistance. [ABSTRACT FROM AUTHOR]

Effects of Nb on the creep resistance and hot corrosion behavior of the Fe-25Cr-35Ni-2.5Al-xNb (x = 0, 0.6, 1.2) Alumina-Forming Austenitic stainless steels (AFA steels) at 700 °C were investigated. The addition of Nb promoted the precipitation of both nanoscale NbC and γ′-Ni3(Al, Nb) phases, which exhibited very low coarsening rate constants. The nanoscale NbC and γ′-Ni3(Al, Nb) phases effectively impeded the migration of dislocations and led to an improvement in creep performance of the Nb-addition AFA steel. The corrosion of AFA steels in Na2SO4-25%K2SO4 at 700 °C was primarily driven by an "oxidation-sulfidation" mechanism. The addition of Nb, serving as a third element, facilitated the formation of protective Cr2O3 and Al2O3 films, which improved the hot corrosion resistance performance. However, the formation Nb2O5 was found to compromise the compactness of the oxide film, which adversely affected the corrosion resistance. [ABSTRACT FROM AUTHOR]

Instrumental data set have revealed several summer precipitation patterns in eastern China, being summarized as "tripole," "dipole" and "coast" modes. The former two have been found to persist at different time scales, leaving the latter unclear in geological records. Here we present 1300‐year hydroclimate records in a tropical maar lake in the southern coast of China using archeal lipid GDGTs, which can reflect lower water redox conditions largely regulated by lake water depth. The down‐core GDGTs reveal a relatively drier condition during the medieval climate anomaly compared to the Little Ice Age, in‐phase with other records in southeast coast of China but opposite to the inland region, hence demonstrating a persistent "coast" mode in eastern China. The thermal state of equatorial Pacific is suggested to play an important role in shaping the "coast" mode by modulating the location and strength of the western Pacific subtropical high and tropical typhoons. Plain Language Summary: Summer precipitations in eastern China affect more than 1 billion people's lives and economic development. It is well‐known that summer precipitations in eastern China show spatial differences. A seesaw pattern of summer precipitations between the southeast coast and the inland region of China, called "coast" mode, has been proposed from modern observations. However, whether this "coast" mode persists in the past remains unexplored. Here, we present a 1300‐year lake‐level record based on GDGTs, a suit of archeal lipids, in a coastal lake of southern China. The result shows a dry medieval climate anomaly and wet Little Ice Age. This result is consistent with other records in southeast coast of China, but in contrast with those in the inland region, thereby proving the persistent of the "coast" mode in the last millennium. The movement of western Pacific subtropical high and tropical typhoon associated with thermal state of the equatorial Pacific could result in this "coast" mode. Key Points: A 1300‐year lake level record based on archeal tetraether lipids in a maar lake on southern coast of ChinaA climate pattern of dry medieval climate anomaly and wet Little Ice Age exists in the southeast coast of ChinaThe thermal state of the equatorial Pacific shapes the coast mode of summer precipitations in eastern China during the last millennium [ABSTRACT FROM AUTHOR]

Climate change has had a widespread and profound impact on global temperature and precipitation patterns, especially in semi-arid areas. Plant δ13C and iWUE indicate the trade-off between carbon uptake and water loss, which is pivotal for understanding plant responses to climate change. Information about the long-term responses of the physiological and ecological processes of different tree species to climate change is also required. To investigate the impact of different forest stand structures and site conditions on long-term growth and physiological processes of coniferous and broad-leaved trees in the mountainous area of Beijing, we analyzed the tree-ring δ13C variation of four tree species (Platycladus orientalis, Pinus tabuliformis, Quercus variabilis, Robinia pseudoacacia) sampled from 64 plots with varying site and stand conditions. We found that the tree-ring δ13C of the four tree species varied from each other and was mainly affected by density and slope aspect, followed by slope and age. Both tree-ring δ13C and iWUE of the four tree species showed increasing trends over time, mechanistically linked to long-term changes in global CO2 concentration. This indicates the four native tree species have adapted well to climate change, and the risk of decline is relatively low. The increased iWUE translated into different growth patterns which varied with tree species, site, and stand condition. Different tree species have varying sensitivities to environmental factors. The iWUE of coniferous tree species is more sensitive to climate change than that of broad-leaved tree species, especially to temperature (T), the Standardized Precipitation Evapotranspiration Index (SPEI), and vapor pressure deficit (VPD). [ABSTRACT FROM AUTHOR]