The rotary kiln and electric furnace melting process is the primary pyrometallurgical method for producing Fe-Ni alloy from nickel laterite.During the drying and preheating stages in the rotary kilns,nickel laterite b...The rotary kiln and electric furnace melting process is the primary pyrometallurgical method for producing Fe-Ni alloy from nickel laterite.During the drying and preheating stages in the rotary kilns,nickel laterite briquettes tend to generate significant amounts of powder because of insufficient heating.These fine powders not only contribute to ring formation within the kiln but also impair the gas permeability of electric furnaces,thereby increasing their power consumption.Replacing the rotary kiln with a traveling grate can significantly improve the strength of reduced briquettes and enhance the discharge temperature.Under a reduction temperature of 1000℃ for 10 min,using green briquettes containing 8 wt.% coal processed through a traveling grate,the reduced briquettes achieved cold compressive strength of 449.7 N/briquette,dropping strength of 88.00%,tumbler strength of 83.49%,Ni metallization degree of 84.80% and Fe metallization degree of 11.16%.Increasing the charging temperature is beneficial to improving the recovery rates of Ni and Fe.Furthermore,an Fe-Ni alloy containing 87.90%Fe and 7.32%Ni was obtained at a smelting temperature of 1575℃ for 45 min with a charging temperature of 1000℃,achieving Ni and Fe recovery rates of 94.91% and 78.67%,respectively.展开更多
Realizing the greater potential for precipitation strengthening in nanograined alloys is highly desirable but often challenging.In this study,an Fe-Ni based alloy was subjected to plastic deformation followed by aging...Realizing the greater potential for precipitation strengthening in nanograined alloys is highly desirable but often challenging.In this study,an Fe-Ni based alloy was subjected to plastic deformation followed by aging treatment to further strengthen nanograins through high-density precipitates.Microstructural characterization showed that nanograins account for∼64%of the volume,with an average size of 44 nm.Notably,the nanoprecipitates in the nanograins exhibit utterly different characteristics from those in the coarse grains.As a result,the sample has an ultra-high yield strength of 1677 MPa.Further analyses indicated that the D0_(24)-structured nanoprecipitates at the nanograin boundaries provide a greater precipitation strengthening than conventional L1_(2)-structured nanoprecipitates within the coarse grains,the reason of which is that the precipitates inhibit partial dislocation emission and grain boundary migration of the nanograins.This work deepens the understanding of precipitation strengthening in nanograined materials and proposes a novel strategy to further strengthen nanograined alloys.展开更多
基金the financial support from the National Natural Science Foundation of China(Nos.52404356 and 52174329)the National Key R&D Program of China(2023YFC3903900 and 2023YFC3903904)Guangxi Key Technologies R&D Program(AA24206042).
文摘The rotary kiln and electric furnace melting process is the primary pyrometallurgical method for producing Fe-Ni alloy from nickel laterite.During the drying and preheating stages in the rotary kilns,nickel laterite briquettes tend to generate significant amounts of powder because of insufficient heating.These fine powders not only contribute to ring formation within the kiln but also impair the gas permeability of electric furnaces,thereby increasing their power consumption.Replacing the rotary kiln with a traveling grate can significantly improve the strength of reduced briquettes and enhance the discharge temperature.Under a reduction temperature of 1000℃ for 10 min,using green briquettes containing 8 wt.% coal processed through a traveling grate,the reduced briquettes achieved cold compressive strength of 449.7 N/briquette,dropping strength of 88.00%,tumbler strength of 83.49%,Ni metallization degree of 84.80% and Fe metallization degree of 11.16%.Increasing the charging temperature is beneficial to improving the recovery rates of Ni and Fe.Furthermore,an Fe-Ni alloy containing 87.90%Fe and 7.32%Ni was obtained at a smelting temperature of 1575℃ for 45 min with a charging temperature of 1000℃,achieving Ni and Fe recovery rates of 94.91% and 78.67%,respectively.
基金support from the National Natural Science Foundation(No.52473339).
文摘Realizing the greater potential for precipitation strengthening in nanograined alloys is highly desirable but often challenging.In this study,an Fe-Ni based alloy was subjected to plastic deformation followed by aging treatment to further strengthen nanograins through high-density precipitates.Microstructural characterization showed that nanograins account for∼64%of the volume,with an average size of 44 nm.Notably,the nanoprecipitates in the nanograins exhibit utterly different characteristics from those in the coarse grains.As a result,the sample has an ultra-high yield strength of 1677 MPa.Further analyses indicated that the D0_(24)-structured nanoprecipitates at the nanograin boundaries provide a greater precipitation strengthening than conventional L1_(2)-structured nanoprecipitates within the coarse grains,the reason of which is that the precipitates inhibit partial dislocation emission and grain boundary migration of the nanograins.This work deepens the understanding of precipitation strengthening in nanograined materials and proposes a novel strategy to further strengthen nanograined alloys.
