Al0.3CrFe1.5MnNi0.5 high entropy alloys(HEA)have special properties.The microstructures and shear strengths of HEA/HEA and HEA/6061-Al joints were determined after direct active soldering(DAS)in air with Sn3.5Ag4Ti ac...Al0.3CrFe1.5MnNi0.5 high entropy alloys(HEA)have special properties.The microstructures and shear strengths of HEA/HEA and HEA/6061-Al joints were determined after direct active soldering(DAS)in air with Sn3.5Ag4Ti active filler at 250°C for 60 s.The results showed that the diffusion of all alloying elements of the HEA alloy was sluggish in the joint area.The joint strengths of HEA/HEA and HEA/6061-Al samples,as analyzed by shear testing,were(14.20±1.63)and(15.70±1.35)MPa,respectively.Observation of the fracture section showed that the HEA/6061-Al soldered joints presented obvious semi-brittle fracture characteristics.展开更多
This research investigated the combined effects of addition of Bi and Sb elements on the microstructure,thermal properties,ultimate tensile strength,ductility,and hardness of Sn−0.7Ag−0.5Cu(SAC0705)solder alloys.The r...This research investigated the combined effects of addition of Bi and Sb elements on the microstructure,thermal properties,ultimate tensile strength,ductility,and hardness of Sn−0.7Ag−0.5Cu(SAC0705)solder alloys.The results indicated that the addition of Bi and Sb significantly reduced the undercooling of solders,refined theβ-Sn phase and extended the eutectic areas of the solders.Moreover,the formation of SbSn and Bi phases in the solder matrix affected the mechanical properties of the solder.With the addition of 3 wt.%Bi and 3 wt.%Sb,the ultimate tensile strength and hardness of the SAC0705 base alloy increased from 31.26 MPa and 15.07 HV to 63.15 MPa and 23.68 HV,respectively.Ductility decreased due to grain boundary strengthening,solid solution strengthening,and precipitation strengthening effects,and the change in the fracture mechanism of the solder alloys.展开更多
The melting point, spreading property, mechanical properties and microstructures of Sn-3.0Ag-2.8Cu solder alloys added with micro-variable-Ce were studied by means of optical microscopy, scanning electron microscopy(S...The melting point, spreading property, mechanical properties and microstructures of Sn-3.0Ag-2.8Cu solder alloys added with micro-variable-Ce were studied by means of optical microscopy, scanning electron microscopy(SEM) and energy dispersive X-ray(EDX). The results indicate that the melting point of Sn-3.0Ag-2.8Cu solder is enhanced by Ce addition; a small amount of Ce will remarkably prolong the creep-rupture life of Sn-3.0Ag-2.8Cu solder joint at room temperature, especially when the content of Ce is 0.1%, the creep-rupture life will be 9 times or more than that of the solder joint without Ce addition; the elongation of Sn-3.0Ag-2.8Cu solder is also obviously improved even up to 15.7%. In sum, the optimum content of Ce is within 0.05%-0.1 %.展开更多
It is known that the strength of alloys can be successfully improved by rapid solidification. The paper presents a process where Cu-Cr-Sn-Zn lead frame alloy is produced by rapid solidification and aging. The microcry...It is known that the strength of alloys can be successfully improved by rapid solidification. The paper presents a process where Cu-Cr-Sn-Zn lead frame alloy is produced by rapid solidification and aging. The microcrystalline structure of rapidly solidified Cu-Cr-Sn-Zn alloy is smaller grain structure examined by optical metallography. The effects of aging processes on the microstructure and properties of the lead frame alloy were investigated. Aged at 500℃ for 15 min the fine coherent precipitates Cr distribute in Cu matrix observed by transmission electron microscopy and the properties of hardness and electrical conductivity properties can reach 178HV and 61%IACS, respectively.展开更多
The effects of Ni content, soldering temperature and time on the IMC thickness in Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.2Co alloys were researched using uniform design method and computer programs. For each alloy, the facto...The effects of Ni content, soldering temperature and time on the IMC thickness in Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.2Co alloys were researched using uniform design method and computer programs. For each alloy, the factors were divided into three levels in the experiment. Two correlative equations are given by regression. They indicate that the effects of three factors on the function are in the mutual and quadratic forms. And the analysis of variance shows the equations are sound and meaningful. Using the equations, it is easy to search, predict and control the IMC thickness. The existence of element Co accelerates the crystallization and growing up of IMC.展开更多
Cu-Cr-Sn-Zn alloys are one of the most popular lead frame alloys due to their high thermal and electrical conductivity as well as high strength. The effects of microstructure and aging processes on hardness and electr...Cu-Cr-Sn-Zn alloys are one of the most popular lead frame alloys due to their high thermal and electrical conductivity as well as high strength. The effects of microstructure and aging processes on hardness and electrical conductivity of Cu-Cr-Sn-Zn alloy were studied. At 450 ℃ aging for 1 h the fine and ordered precipitates Cr are found and are coherent with Cu matrix. Small and fine Cr precipitates make the Cu-Cr-Sn-Zn lead frame alloy possesses higher hardness and conductivity. At 450 ℃ for 3～6 h,the hardness and electrical conductivity can reach 122～106 HV and 68% IACS -70% IACS,respectively. Hardness 113～109 HV and conductivity 66% IACS -69% IACS are available at 500 ℃ aging for 2～3 h.展开更多
Trace amounts of La were utilized to improve the melting behaviors,microstructures,tensile properties and microhardness of Sn-3.0Ag-0.5Cu lead-free solder alloy. La has little effect on the melting behavior of Sn-3.0A...Trace amounts of La were utilized to improve the melting behaviors,microstructures,tensile properties and microhardness of Sn-3.0Ag-0.5Cu lead-free solder alloy. La has little effect on the melting behavior of Sn-3.0Ag-0.5Cu alloy according to the differential thermal analysis(DTA) tests. The X-ray diffraction(XRD) patterns show that β-Sn,Ag3Sn and Cu6Sn5 coexist in the as-cast solder alloys and LaSn3 phases emerge when adding 0.4% La. The microstructures modified by La are more uniform and much finer than that of baseline alloy,and the coarse LaSn3 particles with complex dendrites are observed by optical microscopy(OM) and scanning electron microscopy(SEM) when the addition of La is up to 0.4%. The composition of the LaSn3 phases is identified by energy-dispersive spectroscopy(EDS). There are considerable improvements in mechanical properties with 0.05% and 0.1% addition,but degenerations by adding 0.4%La. The Vickers microhardness of β-Sn and eutectic area are both enhanced with the addition of La and the microhardness of LaSn3 is much larger than those of β-Sn and eutectic area.展开更多
Ag-Sn-Cu-Bi-Ni alloy was internally oxidized in air. The phase constitution,surface morphology and microstructure evolution of the alloy after internal oxidation were analyzed by X-ray diffractometry,optical microscop...Ag-Sn-Cu-Bi-Ni alloy was internally oxidized in air. The phase constitution,surface morphology and microstructure evolution of the alloy after internal oxidation were analyzed by X-ray diffractometry,optical microscopy and scanning electron microscopy,respectively. The results show that the surface color of samples after internal oxidation is different from the different oxidation time and temperatures. The oxidation reaction firstly takes place on the grain boundaries. The microstructure developed on the initial stage of internal oxidation is fir-tree crystal texture. However,this texture structure disappears accompanied by grain growth and oxides forming during the prolonged oxidation. Finally,the oxide particles are uniformly dispersed in the silver matrix.展开更多
基金financial support of this work from the Ministry of Science and Technology, Taibei, China, under Projects No. MOST 105-ET-E-020002-ET, 105-2622-E-020-003-CC3
文摘Al0.3CrFe1.5MnNi0.5 high entropy alloys(HEA)have special properties.The microstructures and shear strengths of HEA/HEA and HEA/6061-Al joints were determined after direct active soldering(DAS)in air with Sn3.5Ag4Ti active filler at 250°C for 60 s.The results showed that the diffusion of all alloying elements of the HEA alloy was sluggish in the joint area.The joint strengths of HEA/HEA and HEA/6061-Al samples,as analyzed by shear testing,were(14.20±1.63)and(15.70±1.35)MPa,respectively.Observation of the fracture section showed that the HEA/6061-Al soldered joints presented obvious semi-brittle fracture characteristics.
基金supported by the Division of Physical Science,Faculty of Science,Prince of Songkla University (PSU),Thailand
文摘This research investigated the combined effects of addition of Bi and Sb elements on the microstructure,thermal properties,ultimate tensile strength,ductility,and hardness of Sn−0.7Ag−0.5Cu(SAC0705)solder alloys.The results indicated that the addition of Bi and Sb significantly reduced the undercooling of solders,refined theβ-Sn phase and extended the eutectic areas of the solders.Moreover,the formation of SbSn and Bi phases in the solder matrix affected the mechanical properties of the solder.With the addition of 3 wt.%Bi and 3 wt.%Sb,the ultimate tensile strength and hardness of the SAC0705 base alloy increased from 31.26 MPa and 15.07 HV to 63.15 MPa and 23.68 HV,respectively.Ductility decreased due to grain boundary strengthening,solid solution strengthening,and precipitation strengthening effects,and the change in the fracture mechanism of the solder alloys.
基金Project(2002E111) supported by the National Basic Research Priorities Program of Shanxi Province, ChinaPorject(03JC14) supported by the Industry Project of Shanxi Province Education, China
文摘The melting point, spreading property, mechanical properties and microstructures of Sn-3.0Ag-2.8Cu solder alloys added with micro-variable-Ce were studied by means of optical microscopy, scanning electron microscopy(SEM) and energy dispersive X-ray(EDX). The results indicate that the melting point of Sn-3.0Ag-2.8Cu solder is enhanced by Ce addition; a small amount of Ce will remarkably prolong the creep-rupture life of Sn-3.0Ag-2.8Cu solder joint at room temperature, especially when the content of Ce is 0.1%, the creep-rupture life will be 9 times or more than that of the solder joint without Ce addition; the elongation of Sn-3.0Ag-2.8Cu solder is also obviously improved even up to 15.7%. In sum, the optimum content of Ce is within 0.05%-0.1 %.
基金supported by the Startup Foundationfor Doctor Scientific Research in Henan University of Sci-ence and Technology (No. 20061009) the Special Fundfor Important Forepart Research in Henan University ofScience and Technology (No. 2008ZD003)the Na-tional Natural Science Foundation of China under grantNo. 50771042.
文摘It is known that the strength of alloys can be successfully improved by rapid solidification. The paper presents a process where Cu-Cr-Sn-Zn lead frame alloy is produced by rapid solidification and aging. The microcrystalline structure of rapidly solidified Cu-Cr-Sn-Zn alloy is smaller grain structure examined by optical metallography. The effects of aging processes on the microstructure and properties of the lead frame alloy were investigated. Aged at 500℃ for 15 min the fine coherent precipitates Cr distribute in Cu matrix observed by transmission electron microscopy and the properties of hardness and electrical conductivity properties can reach 178HV and 61%IACS, respectively.
文摘The effects of Ni content, soldering temperature and time on the IMC thickness in Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.2Co alloys were researched using uniform design method and computer programs. For each alloy, the factors were divided into three levels in the experiment. Two correlative equations are given by regression. They indicate that the effects of three factors on the function are in the mutual and quadratic forms. And the analysis of variance shows the equations are sound and meaningful. Using the equations, it is easy to search, predict and control the IMC thickness. The existence of element Co accelerates the crystallization and growing up of IMC.
文摘Cu-Cr-Sn-Zn alloys are one of the most popular lead frame alloys due to their high thermal and electrical conductivity as well as high strength. The effects of microstructure and aging processes on hardness and electrical conductivity of Cu-Cr-Sn-Zn alloy were studied. At 450 ℃ aging for 1 h the fine and ordered precipitates Cr are found and are coherent with Cu matrix. Small and fine Cr precipitates make the Cu-Cr-Sn-Zn lead frame alloy possesses higher hardness and conductivity. At 450 ℃ for 3～6 h,the hardness and electrical conductivity can reach 122～106 HV and 68% IACS -70% IACS,respectively. Hardness 113～109 HV and conductivity 66% IACS -69% IACS are available at 500 ℃ aging for 2～3 h.
文摘Trace amounts of La were utilized to improve the melting behaviors,microstructures,tensile properties and microhardness of Sn-3.0Ag-0.5Cu lead-free solder alloy. La has little effect on the melting behavior of Sn-3.0Ag-0.5Cu alloy according to the differential thermal analysis(DTA) tests. The X-ray diffraction(XRD) patterns show that β-Sn,Ag3Sn and Cu6Sn5 coexist in the as-cast solder alloys and LaSn3 phases emerge when adding 0.4% La. The microstructures modified by La are more uniform and much finer than that of baseline alloy,and the coarse LaSn3 particles with complex dendrites are observed by optical microscopy(OM) and scanning electron microscopy(SEM) when the addition of La is up to 0.4%. The composition of the LaSn3 phases is identified by energy-dispersive spectroscopy(EDS). There are considerable improvements in mechanical properties with 0.05% and 0.1% addition,but degenerations by adding 0.4%La. The Vickers microhardness of β-Sn and eutectic area are both enhanced with the addition of La and the microhardness of LaSn3 is much larger than those of β-Sn and eutectic area.
基金Project (2006BAE03B03) supported by the Key Project of 11th Five-Year Plan of China
文摘Ag-Sn-Cu-Bi-Ni alloy was internally oxidized in air. The phase constitution,surface morphology and microstructure evolution of the alloy after internal oxidation were analyzed by X-ray diffractometry,optical microscopy and scanning electron microscopy,respectively. The results show that the surface color of samples after internal oxidation is different from the different oxidation time and temperatures. The oxidation reaction firstly takes place on the grain boundaries. The microstructure developed on the initial stage of internal oxidation is fir-tree crystal texture. However,this texture structure disappears accompanied by grain growth and oxides forming during the prolonged oxidation. Finally,the oxide particles are uniformly dispersed in the silver matrix.
