The oxidation behavior of Hastelloy C-2000 alloy was investigated in air at 800 °C and 1000 °C for 100 h, respectively. Oxidation kinetics and oxide scales morphologies were examined by mass gain measurement...The oxidation behavior of Hastelloy C-2000 alloy was investigated in air at 800 °C and 1000 °C for 100 h, respectively. Oxidation kinetics and oxide scales morphologies were examined by mass gain measurement, scanning electron microscopy（SEM）, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The oxidation behavior of the alloy approximately follows a parabolic rate law. Moreover, annealing twins defect structure in matrix deteriorates the oxidation resistance of alloy due to the improvement of diffusion rates for alloying elements and oxygen atoms. At 800 °C, the microstructure is primarily composed of Ni O and Cr1.3Fe0.7O6 and the initial annealing twins structure is visible and Mo-rich phases are emerged to approach boundary of oxide scales. At 1000 °C, however, the morphology microstructure of oxide scales consists of oxide particle with fine Cr oxides and large Ni oxides by inlaying each other, whilst Mo-rich phases hardly appear closing to the interface of oxide scales.展开更多
The texture evolution,twin crystallographic nature and grain orientation variation during the solution heat treatment process of the 304 stainless steel pipe were studied.It was found that after the solution heat trea...The texture evolution,twin crystallographic nature and grain orientation variation during the solution heat treatment process of the 304 stainless steel pipe were studied.It was found that after the solution heat treatment,the texture type clearly changed,and the texture strength was greatly increased.During the solution heat treatment process,grain boundaries migrated along the orientation available for grain growth,giving rise to abnormal growth of some grains through merging with the adjacent small grains.After the solution heat treatment,more<111>60°twins formed in the microstructures of the 304 stainless steel pipe,and the fraction of the twin boundaries showed a pronounced increase.Analysis of the twin crystallographic nature of the FCC crystals showed that four kinds of twin variants can be formed within austenite parent grains,and twelve kinds of misorientations can be formed between the austenite parent grains and the secondary twins.展开更多
The evolution of microstructure,textures,and mechanical properties of thin-walled copper tube during heat treatment was investigated using EBSD technique and tensile test.The results show that the initial deformation ...The evolution of microstructure,textures,and mechanical properties of thin-walled copper tube during heat treatment was investigated using EBSD technique and tensile test.The results show that the initial deformation textures of pre-drawn thin-walled copper tube are mainly composed of Copper and Y components,while with the increase of temperatures,the textures are transformed into a strong Goss texture gradually.The high-resolution microstructural characterizations indicate that the new Goss recrystallized grains nucleate and grow up within the deformed Copper grains and Y grains in different mechanisms,respectively.The tensile strength of the thin-walled copper tube decreases gradually with the increase of the temperature,while the elongation increases first and then decreases sharply due to the action of grain sizes and texture components.展开更多
基金Project(2013AA031004)supported by the National High-tech Research and Development Program of China
文摘The oxidation behavior of Hastelloy C-2000 alloy was investigated in air at 800 °C and 1000 °C for 100 h, respectively. Oxidation kinetics and oxide scales morphologies were examined by mass gain measurement, scanning electron microscopy（SEM）, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The oxidation behavior of the alloy approximately follows a parabolic rate law. Moreover, annealing twins defect structure in matrix deteriorates the oxidation resistance of alloy due to the improvement of diffusion rates for alloying elements and oxygen atoms. At 800 °C, the microstructure is primarily composed of Ni O and Cr1.3Fe0.7O6 and the initial annealing twins structure is visible and Mo-rich phases are emerged to approach boundary of oxide scales. At 1000 °C, however, the morphology microstructure of oxide scales consists of oxide particle with fine Cr oxides and large Ni oxides by inlaying each other, whilst Mo-rich phases hardly appear closing to the interface of oxide scales.
基金Project(51875547)supported by the National Natural Science Foundation of China。
文摘The texture evolution,twin crystallographic nature and grain orientation variation during the solution heat treatment process of the 304 stainless steel pipe were studied.It was found that after the solution heat treatment,the texture type clearly changed,and the texture strength was greatly increased.During the solution heat treatment process,grain boundaries migrated along the orientation available for grain growth,giving rise to abnormal growth of some grains through merging with the adjacent small grains.After the solution heat treatment,more<111>60°twins formed in the microstructures of the 304 stainless steel pipe,and the fraction of the twin boundaries showed a pronounced increase.Analysis of the twin crystallographic nature of the FCC crystals showed that four kinds of twin variants can be formed within austenite parent grains,and twelve kinds of misorientations can be formed between the austenite parent grains and the secondary twins.
基金financially supported by the China Postdoctoral Science Foundation(No.2019M662276)the Chinese Academy of Science and Technology Service Network Planning(No.KFJ-STS-QYZD-145)。
文摘The evolution of microstructure,textures,and mechanical properties of thin-walled copper tube during heat treatment was investigated using EBSD technique and tensile test.The results show that the initial deformation textures of pre-drawn thin-walled copper tube are mainly composed of Copper and Y components,while with the increase of temperatures,the textures are transformed into a strong Goss texture gradually.The high-resolution microstructural characterizations indicate that the new Goss recrystallized grains nucleate and grow up within the deformed Copper grains and Y grains in different mechanisms,respectively.The tensile strength of the thin-walled copper tube decreases gradually with the increase of the temperature,while the elongation increases first and then decreases sharply due to the action of grain sizes and texture components.
