Granitoids and related pegmatitic rare-metal deposits are widespread in China’s Altay region,they used to be considered as Hercynian rocks and mineral deposits.Reported here are the^40Ar^39Ar ages of potassium-rich m...Granitoids and related pegmatitic rare-metal deposits are widespread in China’s Altay region,they used to be considered as Hercynian rocks and mineral deposits.Reported here are the^40Ar^39Ar ages of potassium-rich minerals (muscovite and microcline)in the Koktokay pegmatitic rare-metal orefield and whole-rock as well as quartz fluid-inclusion Rb-Sr isochron ages of granite and ores in the Shangkelan pegmatite rare-metal orefield. The ages indicate that there are Yanshanian Diagenetic Mineralization events happening in China’s Altay orogenic belt and that formation of the famous Koktokay No.3 pegmatitic rare-metal deposit endured about 30 Ma of magmatic crystallization differentiation.展开更多
Microalloying of Ti–6Al–4V alloy by Fe addition has attracted interest as a promising way to improve castability and comprehensive mechanical performance.The mission of this work is twofold by employing the experime...Microalloying of Ti–6Al–4V alloy by Fe addition has attracted interest as a promising way to improve castability and comprehensive mechanical performance.The mission of this work is twofold by employing the experimental examination and the phenomenological analysis,(1)to investigate the effect of Fe addition on the microstructure features and mechanical properties of the Fe-containing Ti–6Al–4V(TC4-xF)alloys subjected to casting and homogenization treatment,and(2)to unveil the critical microstructure features in homogenization,hot-worked and aging treated alloys,respectively,that benefit the yield strength and the fracture toughness.Experimental observations evidence that the addition of 0.5 wt.%Fe is most effective in enhancing the tensile ductility and the modeⅠfracture toughness.Further Fe addition up to 0.7–0.9 wt.%results in plateau values of yield and ultimate strengths with some fluctuations.Phenomenological analyses screen out the microstructural strengthening and toughening determinants which exhibit distinct sensitivities on Fe content under different processing conditions.The solid solution strengthening is confirmed as the primary effect that governs the yield strength of the homogenization treated TC4-xF alloys,followed by the refined size of colony andαlamella,so does it for the hot-worked and the aging-treated alloys.The strengthening effect of Fe could be further promoted by hot-working but impaired by a prolonged annealing time or a lowered cooling rate.The type of crack propagation path and theαmorphology are discerned to play their own leading roles in different cases to influence the performance of fracture toughness.A long crack propagation distance that traverses broadα/βlamellae embraces a high crack propagation resistance and gives rise to enhanced fracture toughness.The experimental results enrich the dataset of microstructure features and mechanical properties of Ti–6Al–4V relevant alloys.While upon the phenomenological analysis,the discovered microstructural strengthening and toughening factors provide deeper mechanism insights into the mechanical behaviors of Fe-modified Ti-6Al-4V alloys and are of the technical importance to future machine-learning of microstructure-property relationship.展开更多
文摘Granitoids and related pegmatitic rare-metal deposits are widespread in China’s Altay region,they used to be considered as Hercynian rocks and mineral deposits.Reported here are the^40Ar^39Ar ages of potassium-rich minerals (muscovite and microcline)in the Koktokay pegmatitic rare-metal orefield and whole-rock as well as quartz fluid-inclusion Rb-Sr isochron ages of granite and ores in the Shangkelan pegmatite rare-metal orefield. The ages indicate that there are Yanshanian Diagenetic Mineralization events happening in China’s Altay orogenic belt and that formation of the famous Koktokay No.3 pegmatitic rare-metal deposit endured about 30 Ma of magmatic crystallization differentiation.
基金sponsored by the National Natural Science Foundation of China(Grant No.51801101)the Natural Science Foundation of Jiangsu Province(Grant No.BE2019119)
文摘Microalloying of Ti–6Al–4V alloy by Fe addition has attracted interest as a promising way to improve castability and comprehensive mechanical performance.The mission of this work is twofold by employing the experimental examination and the phenomenological analysis,(1)to investigate the effect of Fe addition on the microstructure features and mechanical properties of the Fe-containing Ti–6Al–4V(TC4-xF)alloys subjected to casting and homogenization treatment,and(2)to unveil the critical microstructure features in homogenization,hot-worked and aging treated alloys,respectively,that benefit the yield strength and the fracture toughness.Experimental observations evidence that the addition of 0.5 wt.%Fe is most effective in enhancing the tensile ductility and the modeⅠfracture toughness.Further Fe addition up to 0.7–0.9 wt.%results in plateau values of yield and ultimate strengths with some fluctuations.Phenomenological analyses screen out the microstructural strengthening and toughening determinants which exhibit distinct sensitivities on Fe content under different processing conditions.The solid solution strengthening is confirmed as the primary effect that governs the yield strength of the homogenization treated TC4-xF alloys,followed by the refined size of colony andαlamella,so does it for the hot-worked and the aging-treated alloys.The strengthening effect of Fe could be further promoted by hot-working but impaired by a prolonged annealing time or a lowered cooling rate.The type of crack propagation path and theαmorphology are discerned to play their own leading roles in different cases to influence the performance of fracture toughness.A long crack propagation distance that traverses broadα/βlamellae embraces a high crack propagation resistance and gives rise to enhanced fracture toughness.The experimental results enrich the dataset of microstructure features and mechanical properties of Ti–6Al–4V relevant alloys.While upon the phenomenological analysis,the discovered microstructural strengthening and toughening factors provide deeper mechanism insights into the mechanical behaviors of Fe-modified Ti-6Al-4V alloys and are of the technical importance to future machine-learning of microstructure-property relationship.
