An Al 50wt%TiC composite was directly synthesized by self propagating high temperature synthesis (SHS) technology,and then was used as a grain refining master alloy for commercially pure aluminum.The microstructure...An Al 50wt%TiC composite was directly synthesized by self propagating high temperature synthesis (SHS) technology,and then was used as a grain refining master alloy for commercially pure aluminum.The microstructure and grain refining performance of the synthesized master alloy were emphatically investigated.The SHS master alloy only contained submicron TiC particles except for Al matrix.Moreover,TiC particles were relatively free of agglomeration. Grain refining tests show that adding only 0.1 wt% of the master alloys to the aluminum melt could transform the structure of the solidified samples from coarse columnar grains to fine equiaxed grains (average grain size 120μm),and that this grain refining effectiveness could be maintained for almost 1.5h at 1003K. Therefore,it is concluded that the SHS master alloy is an effective grain refiner for aluminum and its alloys, and that it is highly resistant to the grain refining fading encountered with most grain refiners.展开更多
开发了一种制备Al Ti C晶粒细化剂的新方法———自蔓延高温合成法(SHS)。分别采用直接SHS工艺和铝液中的SHS工艺制备出了所需的晶粒细化剂,结果表明:用SHS工艺直接合成的细化剂由Al和亚微米TiC粒子组成,而铝液中燃烧合成的细化剂则由A...开发了一种制备Al Ti C晶粒细化剂的新方法———自蔓延高温合成法(SHS)。分别采用直接SHS工艺和铝液中的SHS工艺制备出了所需的晶粒细化剂,结果表明:用SHS工艺直接合成的细化剂由Al和亚微米TiC粒子组成,而铝液中燃烧合成的细化剂则由Al、块状Al3Ti和粒状TiC组成。上述两种工艺制备的细化剂对工业纯铝均有良好的晶粒细化效果,但比较而言,铝液中的SHS工艺更适合细化剂的低成本制备。展开更多
A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion （SHS） as heating source. The effect of heating rate on the alumina grain growth was explored...A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion （SHS） as heating source. The effect of heating rate on the alumina grain growth was explored based on this rapid-heating method. Comparing with the alumina prepared by two different heating ratios （greater than 1 000 ℃/min in SItS and about 50 ℃/min in common pressureless sintering furnace）, it was revealed that the rapid heating could promote the grain growth greatly without pressure during sintering. However, if a pressure was applied simultaneously, the grain growth would be almost completely restrained. Since these observations are quite different from the expectation, a new grain growth model was proposed.展开更多
The microstructural evolution and Vickers hardness measurement in the welding heat-affected zone （HAZ） of HD15 Nil MnMoNbCu steel for nuclear power station were investigated by Gleeble-3180 thermal mechanical simula...The microstructural evolution and Vickers hardness measurement in the welding heat-affected zone （HAZ） of HD15 Nil MnMoNbCu steel for nuclear power station were investigated by Gleeble-3180 thermal mechanical simulator, and the simulated HAZ continuous cooling transformation curves （SH-CCT） were measured simultaneously. With ts/5 inereasing from 3.75 s to 15 000 s, the product was obtained martensite, bainite, ferrite and pearlite, successively. The result of microstructure and Vickers hardness in the heat-affected zone was in good agreement with those measured by SH-CCT diagram with the heat input 16. 2 kJ/cm as an example to weld the HD15Ni1MnMoNbCu steel pipe using TIG/SMAW/SAW welding methods.展开更多
A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature（SHS）reaction from an Al-Ti-B_4C system with molten Al.Microstructure and phase characterization of the prepared Al-...A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature（SHS）reaction from an Al-Ti-B_4C system with molten Al.Microstructure and phase characterization of the prepared Al-5Ti-0.75B-0.2C master alloy show that the nearly spherical TiC particles,hexagonal or rectangular TiB_2 particles,and blocklike TiAl_3 particles distribute uniformly in the aluminum matrix.Grain refining test on commercial pure aluminum indicates that Al-5Ti-0.75B-0.2C master alloy exhibits a better grain refining performance than Al-5Ti-lB master alloy.By addition of 0.2 wt%Al-5Ti-0.75B-0.2C master alloy,the average grain size of a-Al can be effectively refined to160 ± 5 μm from about 3000 μm,and the tensile strength and elongation are increased by about 20%and 14.1%due to the grain refinement.展开更多
文摘An Al 50wt%TiC composite was directly synthesized by self propagating high temperature synthesis (SHS) technology,and then was used as a grain refining master alloy for commercially pure aluminum.The microstructure and grain refining performance of the synthesized master alloy were emphatically investigated.The SHS master alloy only contained submicron TiC particles except for Al matrix.Moreover,TiC particles were relatively free of agglomeration. Grain refining tests show that adding only 0.1 wt% of the master alloys to the aluminum melt could transform the structure of the solidified samples from coarse columnar grains to fine equiaxed grains (average grain size 120μm),and that this grain refining effectiveness could be maintained for almost 1.5h at 1003K. Therefore,it is concluded that the SHS master alloy is an effective grain refiner for aluminum and its alloys, and that it is highly resistant to the grain refining fading encountered with most grain refiners.
文摘开发了一种制备Al Ti C晶粒细化剂的新方法———自蔓延高温合成法(SHS)。分别采用直接SHS工艺和铝液中的SHS工艺制备出了所需的晶粒细化剂,结果表明:用SHS工艺直接合成的细化剂由Al和亚微米TiC粒子组成,而铝液中燃烧合成的细化剂则由Al、块状Al3Ti和粒状TiC组成。上述两种工艺制备的细化剂对工业纯铝均有良好的晶粒细化效果,但比较而言,铝液中的SHS工艺更适合细化剂的低成本制备。
基金Funded by the National Natural Science Foundation of China(No.U12301013)the State Ministry of Science and Technology Innovation Fund(No.0102010DFA52240)
文摘A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion （SHS） as heating source. The effect of heating rate on the alumina grain growth was explored based on this rapid-heating method. Comparing with the alumina prepared by two different heating ratios （greater than 1 000 ℃/min in SItS and about 50 ℃/min in common pressureless sintering furnace）, it was revealed that the rapid heating could promote the grain growth greatly without pressure during sintering. However, if a pressure was applied simultaneously, the grain growth would be almost completely restrained. Since these observations are quite different from the expectation, a new grain growth model was proposed.
文摘The microstructural evolution and Vickers hardness measurement in the welding heat-affected zone （HAZ） of HD15 Nil MnMoNbCu steel for nuclear power station were investigated by Gleeble-3180 thermal mechanical simulator, and the simulated HAZ continuous cooling transformation curves （SH-CCT） were measured simultaneously. With ts/5 inereasing from 3.75 s to 15 000 s, the product was obtained martensite, bainite, ferrite and pearlite, successively. The result of microstructure and Vickers hardness in the heat-affected zone was in good agreement with those measured by SH-CCT diagram with the heat input 16. 2 kJ/cm as an example to weld the HD15Ni1MnMoNbCu steel pipe using TIG/SMAW/SAW welding methods.
基金supported by the Scientific and Technical Project of Sichuan Province(Nos.13CGZHZX0200,2014GZX0064,2015GZ0057)
文摘A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature（SHS）reaction from an Al-Ti-B_4C system with molten Al.Microstructure and phase characterization of the prepared Al-5Ti-0.75B-0.2C master alloy show that the nearly spherical TiC particles,hexagonal or rectangular TiB_2 particles,and blocklike TiAl_3 particles distribute uniformly in the aluminum matrix.Grain refining test on commercial pure aluminum indicates that Al-5Ti-0.75B-0.2C master alloy exhibits a better grain refining performance than Al-5Ti-lB master alloy.By addition of 0.2 wt%Al-5Ti-0.75B-0.2C master alloy,the average grain size of a-Al can be effectively refined to160 ± 5 μm from about 3000 μm,and the tensile strength and elongation are increased by about 20%and 14.1%due to the grain refinement.
