THIS paper introduces a new type of platinum-group elements (PGE) mineralization formed under a special condition of intermediate to low temperature, i. e. Huanggang PGE-As-Co deposit related to cryptoex-plosive hornb...THIS paper introduces a new type of platinum-group elements (PGE) mineralization formed under a special condition of intermediate to low temperature, i. e. Huanggang PGE-As-Co deposit related to cryptoex-plosive hornblendite, Inner Mongolia, of which the proven reserves of arsenic reached small size. 1 Geology of mineral district Huanggang PGE-As-Co deposit, located at the margin of Huanggang Mesozoic volcanic basin in thesouthern part of Da Hinggan Range, was controlled by both Huanggang-Ganzhuermiao deep fracture andvolcanic apparatus. The volcanic apparatus in a protruding cupola land-form is about 0.25 km^2. It wasfilled with rhyolitic volcanic breccia, brecciated tuff, subvolcanic dacite porphyry and brecciated lava ofvolcanic neck facies. The host hornblendite, of which Rb-Sr isochron age (bulk rock) is (90.66 ±14.44) Ma, intruded into the apparatus in the form of irregular dike (figure 1).展开更多
The tensile properties and deformation behavior of several cast Ni-based superalloys, respectively, in the equiaxed, columnar-crystal and single-crystal styles are comparatively studied. The effects of solidification ...The tensile properties and deformation behavior of several cast Ni-based superalloys, respectively, in the equiaxed, columnar-crystal and single-crystal styles are comparatively studied. The effects of solidification way, heat treatment and strain rate on the tensile properties are discussed in detail. It is found that the reduction of grain boundaries by the feasible solidification ways offers cast Ni-based superalloys the potential capability of improving the mechanical properties, the ultimate achievement of which is also confirmed to lie on the appropriate modifications of chemical composition and heat treatment. The prolongation of solid solution facilitates the precipitation of fine secondary γ＇ phase, whereas the extension of high-temperature aging leads to the coarsening of secondary γ＇ phase. The combination of these two aspects has a crucial influence on the tensile properties. Under tensile applied stress, the surface grains of DZ-A alloy deform slightly, while the inner grains deform heavily. This deformation inhomogeneity is ascribed to the occurrence of cracks or oblique grains near the surface of specimens and the sliding or decohesion of grain boundaries between the surface and inner grains. Regardless of strain rate, the ILTDM （intermediate-low-temperature ductility minimum） phe- nomenon always happens in the temperature range from 400 to 600 ℃ in all the investigated alloys, the occurrence of which is closely related to the strong strain-hardening behavior in the deformation process. Finally, the interaction of slip bands which are the main deformation mode below 600 ℃ is established to be the essential reason for the strain hardening.展开更多
文摘THIS paper introduces a new type of platinum-group elements (PGE) mineralization formed under a special condition of intermediate to low temperature, i. e. Huanggang PGE-As-Co deposit related to cryptoex-plosive hornblendite, Inner Mongolia, of which the proven reserves of arsenic reached small size. 1 Geology of mineral district Huanggang PGE-As-Co deposit, located at the margin of Huanggang Mesozoic volcanic basin in thesouthern part of Da Hinggan Range, was controlled by both Huanggang-Ganzhuermiao deep fracture andvolcanic apparatus. The volcanic apparatus in a protruding cupola land-form is about 0.25 km^2. It wasfilled with rhyolitic volcanic breccia, brecciated tuff, subvolcanic dacite porphyry and brecciated lava ofvolcanic neck facies. The host hornblendite, of which Rb-Sr isochron age (bulk rock) is (90.66 ±14.44) Ma, intruded into the apparatus in the form of irregular dike (figure 1).
基金supported by the National Natural Science Foundation of China(No.51001101)the National Energy Administration Program of China(No.NY20150102)
文摘The tensile properties and deformation behavior of several cast Ni-based superalloys, respectively, in the equiaxed, columnar-crystal and single-crystal styles are comparatively studied. The effects of solidification way, heat treatment and strain rate on the tensile properties are discussed in detail. It is found that the reduction of grain boundaries by the feasible solidification ways offers cast Ni-based superalloys the potential capability of improving the mechanical properties, the ultimate achievement of which is also confirmed to lie on the appropriate modifications of chemical composition and heat treatment. The prolongation of solid solution facilitates the precipitation of fine secondary γ＇ phase, whereas the extension of high-temperature aging leads to the coarsening of secondary γ＇ phase. The combination of these two aspects has a crucial influence on the tensile properties. Under tensile applied stress, the surface grains of DZ-A alloy deform slightly, while the inner grains deform heavily. This deformation inhomogeneity is ascribed to the occurrence of cracks or oblique grains near the surface of specimens and the sliding or decohesion of grain boundaries between the surface and inner grains. Regardless of strain rate, the ILTDM （intermediate-low-temperature ductility minimum） phe- nomenon always happens in the temperature range from 400 to 600 ℃ in all the investigated alloys, the occurrence of which is closely related to the strong strain-hardening behavior in the deformation process. Finally, the interaction of slip bands which are the main deformation mode below 600 ℃ is established to be the essential reason for the strain hardening.
