Three novel multi-microalloying TiAl-based alloys containing high Nb were designed and fabricated Thermogravimetric method was applied to investigate the influence of Cr on the oxidation behavior of high Nb TiAl alloy...Three novel multi-microalloying TiAl-based alloys containing high Nb were designed and fabricated Thermogravimetric method was applied to investigate the influence of Cr on the oxidation behavior of high Nb TiAl alloy at 1,073 K for 200 h in laboratory air. The 2 at.% and 4 at.% Cr were added into the alloy,(respectivel named 2 Cr and 4 Cr compared to the Cr-free ternary alloy, 0 Cr alloy). The alloys' microstructure and compositio as well as the composition distribution of the oxidation scale were analyzed by means of Scanning Electro Microscopy(SEM), Energy Dispersive Spectroscopy(EDS), and X-Ray Diffractometry(XRD). The results show that the addition of Cr decreases the grain size of the Nb-TiAl alloy and leads to a transformation from a full lamellar structure to a nearly fully lamellar structure. When oxidized at 1,073 K for 200 h, the oxidized mass gai of the alloy increases with an increase in Cr addition amount in the first 100 h and decreases in the last 100 h With the increase of Cr content, the oxidation surface turns compact but uneven in morphology, which may affec the oxidation resistance of the alloy by increasing the peeling off risk of the oxidation layer at friction conditions.展开更多
DEAR EDITOR,The giant panda(Ailuropoda melanoleuca)is a unique forest-dwelling species endemic to China.Previous studies have suggested that giant pandas are heavily reliant on old-growth forests with high vegetation ...DEAR EDITOR,The giant panda(Ailuropoda melanoleuca)is a unique forest-dwelling species endemic to China.Previous studies have suggested that giant pandas are heavily reliant on old-growth forests with high vegetation coverage.As such,management has primarily focused on improving vegetation coverage in the potential range of giant pandas to increase the availability of suitable habitat.However,it remains unclear whether high vegetation coverage itself results in higher giant panda density.Here,we analyzed changes in vegetation coverage from 2001 to 2011 as well as the occurrence of wild giant pandas in five mountain areas.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities of Ministry of Education of China(Grant Nos.HEUCFP 201731 and 201719)
文摘Three novel multi-microalloying TiAl-based alloys containing high Nb were designed and fabricated Thermogravimetric method was applied to investigate the influence of Cr on the oxidation behavior of high Nb TiAl alloy at 1,073 K for 200 h in laboratory air. The 2 at.% and 4 at.% Cr were added into the alloy,(respectivel named 2 Cr and 4 Cr compared to the Cr-free ternary alloy, 0 Cr alloy). The alloys' microstructure and compositio as well as the composition distribution of the oxidation scale were analyzed by means of Scanning Electro Microscopy(SEM), Energy Dispersive Spectroscopy(EDS), and X-Ray Diffractometry(XRD). The results show that the addition of Cr decreases the grain size of the Nb-TiAl alloy and leads to a transformation from a full lamellar structure to a nearly fully lamellar structure. When oxidized at 1,073 K for 200 h, the oxidized mass gai of the alloy increases with an increase in Cr addition amount in the first 100 h and decreases in the last 100 h With the increase of Cr content, the oxidation surface turns compact but uneven in morphology, which may affec the oxidation resistance of the alloy by increasing the peeling off risk of the oxidation layer at friction conditions.
基金supported by the National Natural Science Foundation of China(U21A20193)Chengdu Giant Panda Breeding Research Foundation(CPF2017-20)。
文摘DEAR EDITOR,The giant panda(Ailuropoda melanoleuca)is a unique forest-dwelling species endemic to China.Previous studies have suggested that giant pandas are heavily reliant on old-growth forests with high vegetation coverage.As such,management has primarily focused on improving vegetation coverage in the potential range of giant pandas to increase the availability of suitable habitat.However,it remains unclear whether high vegetation coverage itself results in higher giant panda density.Here,we analyzed changes in vegetation coverage from 2001 to 2011 as well as the occurrence of wild giant pandas in five mountain areas.
