The influence of high temperature repressing treatment on the segregation of phosphorus in the 93W alloy was carefully investigated by means of Auger electron spectroscope,EPMA, TEM and SEM.The segregation of phosphor...The influence of high temperature repressing treatment on the segregation of phosphorus in the 93W alloy was carefully investigated by means of Auger electron spectroscope,EPMA, TEM and SEM.The segregation of phosphorus has been observed at the tungsten-tungsten grain boundaries,particularly at the tungsten-matrix interphases when the specimens were kept at the temperature in the range of 1200—1500℃ ,followed by furnace cooling.However, no segregation of phosphorus was observed at the interfaces after the specimens were re- pressed at the range of temperature,followed by furnace cooling.After investigation,the dis- locations in the matrix phase of as-repressed specimens directly influenced the phosphorus segregation to the interfaces.After annealing,the mechanical properties were reduced because of the phosphorus segregation at the interface boundaries.展开更多
Annealing treatment has a strong effect on mechanical Properties of cold worked tungsten-nickel-iron heavy alloys. A 93W-4.5Ni-2.5Fe alloy swaged 15% was annealed from 500 to 1350℃ to investigate the changes in micro...Annealing treatment has a strong effect on mechanical Properties of cold worked tungsten-nickel-iron heavy alloys. A 93W-4.5Ni-2.5Fe alloy swaged 15% was annealed from 500 to 1350℃ to investigate the changes in microstructure and their effects on mechanical properties. Recrystallization of W particles takes place during annealing treatments above 800℃ and the microhardnesses reduces rapidly. High density of dislocations in the, matrix phase after annealing treatment at 1350℃ suggests that recrystallization of the matrix phase has not taken place. A small decrease in microhardness of the matrix phase is caused by recovery during the annealing treatments.The changes in mechanical properties of swaged and annealed 93W-4.5 Ni-2.SFe alloy are mainly due to the changes in microstructure of W particles because of their recrystallization.展开更多
The microstructure and properties of the 93W-4Ni-2Co-1Fe(mass fraction,%) tungsten heavy alloys prepared by mechanical alloying and electric current activated sintering from mixed elemental powders were investigated.A...The microstructure and properties of the 93W-4Ni-2Co-1Fe(mass fraction,%) tungsten heavy alloys prepared by mechanical alloying and electric current activated sintering from mixed elemental powders were investigated.After 15 h milling,the average W grain size in the powders is decreased to 120 nm.For the powders milled for 15 h,the density,hardness and transverse rupture strength of the alloys sintered only by an intensive pulse electric current are the maximum.When the total sintering time keeps constant,the properties of the sintered alloys can be obviously improved by optimizing the sintering time of pulse-and constant-currents.A bulk ultrafine alloy with an average W grain size of about 340 nm can be obtained by sintering 15 h-milled powders in a total sintering time of 6 min.The corresponding sintered density,hardness and transverse rupture strength reach 16.78 g /cm3,HRA84.3 and 968 MPa,respectively.展开更多
文摘The influence of high temperature repressing treatment on the segregation of phosphorus in the 93W alloy was carefully investigated by means of Auger electron spectroscope,EPMA, TEM and SEM.The segregation of phosphorus has been observed at the tungsten-tungsten grain boundaries,particularly at the tungsten-matrix interphases when the specimens were kept at the temperature in the range of 1200—1500℃ ,followed by furnace cooling.However, no segregation of phosphorus was observed at the interfaces after the specimens were re- pressed at the range of temperature,followed by furnace cooling.After investigation,the dis- locations in the matrix phase of as-repressed specimens directly influenced the phosphorus segregation to the interfaces.After annealing,the mechanical properties were reduced because of the phosphorus segregation at the interface boundaries.
文摘Annealing treatment has a strong effect on mechanical Properties of cold worked tungsten-nickel-iron heavy alloys. A 93W-4.5Ni-2.5Fe alloy swaged 15% was annealed from 500 to 1350℃ to investigate the changes in microstructure and their effects on mechanical properties. Recrystallization of W particles takes place during annealing treatments above 800℃ and the microhardnesses reduces rapidly. High density of dislocations in the, matrix phase after annealing treatment at 1350℃ suggests that recrystallization of the matrix phase has not taken place. A small decrease in microhardness of the matrix phase is caused by recovery during the annealing treatments.The changes in mechanical properties of swaged and annealed 93W-4.5 Ni-2.SFe alloy are mainly due to the changes in microstructure of W particles because of their recrystallization.
基金Project(2007CB616905) supported by the National Basic Research Program of ChinaProject(2007AA03Z112) supported by the National High-tech Research and Development Program of China+1 种基金Project(x2jqB6080210) supported by the Natural Science Foundation of Guangdong Province,ChinaProject(9140A18040709JW1601) supported by the Advanced Research Fund of Department of Defense,China
文摘The microstructure and properties of the 93W-4Ni-2Co-1Fe(mass fraction,%) tungsten heavy alloys prepared by mechanical alloying and electric current activated sintering from mixed elemental powders were investigated.After 15 h milling,the average W grain size in the powders is decreased to 120 nm.For the powders milled for 15 h,the density,hardness and transverse rupture strength of the alloys sintered only by an intensive pulse electric current are the maximum.When the total sintering time keeps constant,the properties of the sintered alloys can be obviously improved by optimizing the sintering time of pulse-and constant-currents.A bulk ultrafine alloy with an average W grain size of about 340 nm can be obtained by sintering 15 h-milled powders in a total sintering time of 6 min.The corresponding sintered density,hardness and transverse rupture strength reach 16.78 g /cm3,HRA84.3 and 968 MPa,respectively.
