nano-SiCp/A356 composites with different nano-SiCp contents were prepared by squeeze casting after ultrasonic treatment（UT）. The effects of SiCp content on the microstructure and mechanical properties of the nanocom...nano-SiCp/A356 composites with different nano-SiCp contents were prepared by squeeze casting after ultrasonic treatment（UT）. The effects of SiCp content on the microstructure and mechanical properties of the nanocomposites were investigated. Theresults show that with the addition of nano-SiCp, the microstructure of nanocomposites is obviously refined, the morphology of theα（Al） grains transforms from coarse dendrites to rosette crystals, and long acicular eutectic Si phases are shortened and rounded. Themechanical properties of 0.5%, 1% and 2% （mass fraction） SiCp/A356 nanocomposites are improved continuously with the increaseof nano-SiCp content. Especially, when the SiCp content is 2%, the tensile strength, yield strength and elongation are 259 MPa,144 MPa and 5.3%, which are increased by 19%, 69% and 15%, respectively, compared with those of the matrix alloy. Theimprovement of strength is attributed to mechanisms of Hall？Petch strengthening and Orowan strengthening.展开更多
The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic me...The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic method, an investigation has been undertaken by means of Vickers hardness measurement, scanning electron microscopy （SEM） and energy spectrum analyzing apparatus. The box-type heat treatment furnace was used in the study. The results showed that no discontinuous cellular precipitation is observed at the grain boundaries in the magnesium matrix of the composite while the MglTAI12 preferentially precipitates in the matrix. The time to reach the peak hardness for AZ61 alloy or SiCp/AZ61 magnesium matrix composites is reduced with the increase of aging temperature. At the same temperature, the composite exhibit an accelerated aging manner but lower aging efficiency, compared with the unreinforced matrix alloy. The microhardness of the composite is higher than that of the unreinforced matrix alloy, because that the SiC particles distributes homogeneously in the matrix alloy under the ultrasonic processing condition.展开更多
Novel hybrid Cu matrix composites reinforced by graphite(Gr) particle with volume fraction of 5%- 15%and nano-SiC particle(nano-SiCp) with volume fraction of 3%have been prepared by powder metallurgy.The results show ...Novel hybrid Cu matrix composites reinforced by graphite(Gr) particle with volume fraction of 5%- 15%and nano-SiC particle(nano-SiCp) with volume fraction of 3%have been prepared by powder metallurgy.The results show that Gr and nano-SiCp distribute uniformly in the Cu matrix.With increasing the volume fraction of Gr,the tensile strength of the composites decreases from 114 to 51 MPa and the elastic modulus decreases from 75 to 60 GPa.Compared with the sintered composites,the tensile properties including elastic modulus,tensile strength,yield strength and tensile elongation of the hot-extruded(nano-SiCp+Gr)/Cu composites are improved greatly due to higher relative density of the composites and more uniform distribution of Gr and nano-SiCp,in addition to finer grain size of the matrix as a result of dynamic recovery and recrystallization which occur during hot extrusion process.展开更多
基金Project(51574129)supported by the National Natural Science Foundation of ChinaProject(2016209A001)supported by JCKY Foundation,China
文摘nano-SiCp/A356 composites with different nano-SiCp contents were prepared by squeeze casting after ultrasonic treatment（UT）. The effects of SiCp content on the microstructure and mechanical properties of the nanocomposites were investigated. Theresults show that with the addition of nano-SiCp, the microstructure of nanocomposites is obviously refined, the morphology of theα（Al） grains transforms from coarse dendrites to rosette crystals, and long acicular eutectic Si phases are shortened and rounded. Themechanical properties of 0.5%, 1% and 2% （mass fraction） SiCp/A356 nanocomposites are improved continuously with the increaseof nano-SiCp content. Especially, when the SiCp content is 2%, the tensile strength, yield strength and elongation are 259 MPa,144 MPa and 5.3%, which are increased by 19%, 69% and 15%, respectively, compared with those of the matrix alloy. Theimprovement of strength is attributed to mechanisms of Hall？Petch strengthening and Orowan strengthening.
基金financially supported by the National Natural Science Foundation of China(Grant No.50765005)supported by the Innovative Group of Science and Technology of Colleges,Jiangxi Province,China(00008713)
文摘The mechanical properties of magnesium matrix composties can be further improved by aging treatment. To study the aging behavior of SiC particles reinforced AZ61 magnesium matrix composites fabricated by ultrasonic method, an investigation has been undertaken by means of Vickers hardness measurement, scanning electron microscopy （SEM） and energy spectrum analyzing apparatus. The box-type heat treatment furnace was used in the study. The results showed that no discontinuous cellular precipitation is observed at the grain boundaries in the magnesium matrix of the composite while the MglTAI12 preferentially precipitates in the matrix. The time to reach the peak hardness for AZ61 alloy or SiCp/AZ61 magnesium matrix composites is reduced with the increase of aging temperature. At the same temperature, the composite exhibit an accelerated aging manner but lower aging efficiency, compared with the unreinforced matrix alloy. The microhardness of the composite is higher than that of the unreinforced matrix alloy, because that the SiC particles distributes homogeneously in the matrix alloy under the ultrasonic processing condition.
基金the Postdoctoral Science Foundation of Heilongjiang(No.LRB09-603)
文摘Novel hybrid Cu matrix composites reinforced by graphite(Gr) particle with volume fraction of 5%- 15%and nano-SiC particle(nano-SiCp) with volume fraction of 3%have been prepared by powder metallurgy.The results show that Gr and nano-SiCp distribute uniformly in the Cu matrix.With increasing the volume fraction of Gr,the tensile strength of the composites decreases from 114 to 51 MPa and the elastic modulus decreases from 75 to 60 GPa.Compared with the sintered composites,the tensile properties including elastic modulus,tensile strength,yield strength and tensile elongation of the hot-extruded(nano-SiCp+Gr)/Cu composites are improved greatly due to higher relative density of the composites and more uniform distribution of Gr and nano-SiCp,in addition to finer grain size of the matrix as a result of dynamic recovery and recrystallization which occur during hot extrusion process.
