The morphology changes of both Fe-containing intermetallic compounds and the primary Si phase of Al-20Si-2Fe-2Cu-0.4Mg-1.0Ni-0.5Mn (mass fraction, %) alloy produced by semi-solid rheo-diecasting were studied.The semi-...The morphology changes of both Fe-containing intermetallic compounds and the primary Si phase of Al-20Si-2Fe-2Cu-0.4Mg-1.0Ni-0.5Mn (mass fraction, %) alloy produced by semi-solid rheo-diecasting were studied.The semi-solid slurry of high silicon aluminum alloy was prepared by direct ultrasonic vibration (DUV) which was imposed on the alloy near the liquidus temperature for about 2 min.Then, standard test samples of 6.4 mm in diameter were formed by semi-solid rheo-diecasting.The results show that the DUV treatment suppresses the formation of needle-like β-Al5(Fe,Mn)Si phase, and the Fe-containing intermetallic compounds exist in the form of fine Al4(Fe, Mn)Si2 particles.Additionally, the primary Si grows up as fine and round particles with uniform distribution in α(Al) matrix of this alloy under DUV treatment.The tensile strengths of the samples at the room temperature and 573 K are 230 MPa and 145 MPa, respectively.The coefficient of thermal expansion (CTE) between 25 °C and 300 °C is 16.052 8×10-6 °C-1, and the wear rate is 1.55%.The hardness of this alloy with 2% Fe reaches HB146.3.It is discovered that modified morphology and uniform distribution of the Fe-containing intermetallic compounds and the primary Si phase are the main reasons for reducing the CTE and increasing the wear resistance of this alloy.展开更多
In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental...In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo) which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 oC to 400 oC. The impact toughness is 4-11 J?cm-2 at room temperature and the impact展开更多
The P + Sr + Ce compound modification technologies of as-cast Al-21Si-1.5Cu-1.5Ni- 2.5Fe- 0.5Mg alloy were investigated by means of orthogonal test. Orthogonal test results show that 3% (CaH2PO4 + 2CASO4)+ 0.2%...The P + Sr + Ce compound modification technologies of as-cast Al-21Si-1.5Cu-1.5Ni- 2.5Fe- 0.5Mg alloy were investigated by means of orthogonal test. Orthogonal test results show that 3% (CaH2PO4 + 2CASO4)+ 0.2%Sr + 0.2%Ce is the optimum additive of modification treatment which can fine eutectic and primary silicon also can change the form of rich-iron phase at same time. The needle form of rich-iron phase is Al9FeSi3, which is prored by X-ray diffraction analysis and X-ray energy spectrum analysis. After compound modification treatment, the needle form of rich-iron phase disappeared and the fish bone form of rich-iron and rich-Ce phase that is AlsCeFe emerged. Both at room temperature and at 300℃, the tensile strength of the alloy after the modification treatment with the optimum additive is 30% lager than that of the alloy unmodified. Observed by SEM, the brittle intercrystalline tensile fracture changed into a blended one in which has many dimples.展开更多
A high Fe containing aluminum matrix filler metal for hardfacing aluminum silicon alloys has been developed by using iron,nickel,and silicon as the major strengthening elements,and by measuring mechanical properties...A high Fe containing aluminum matrix filler metal for hardfacing aluminum silicon alloys has been developed by using iron,nickel,and silicon as the major strengthening elements,and by measuring mechanical properties,room temperature and high temperature wear tests,and microstructural analysis.The filler metal,which contains 3.0%-5.0% Fe and 11.0%-13.0% Si,exhibits an excellent weldability.The as cast and as welded microstructures for the filler metal are of uniformly distribution and its dispersed network of hard phase is enriched with Al Si Fe Ni.The filler metal shows high mechanical properties and wear resistance at both room temperature and high temperatures.The deposited metal has a better resistance to impact wear at 220℃ than that of substrate Al Si Mg Cu piston alloy;at room temperature,the deposited metal has an equivalent resistance to slide wear with lubrication as that of a hyper eutectic aluminum silicon alloy with 27% Si and 1% Ni.展开更多
With tank special purpose lubricating oil,100N,200N and 800N loading force and different loading times,spray-formed high-silicon aluminium alloy and military superpower engine steel cylinder sleeve materials were used...With tank special purpose lubricating oil,100N,200N and 800N loading force and different loading times,spray-formed high-silicon aluminium alloy and military superpower engine steel cylinder sleeve materials were used for comparative friction test and friction pair comparision test under simulated engine work condition.The results showed that,compared with steel cylinder sleeve materials,high-silicon aluminium alloy showed more excellent wearing resistance.The friction mechanism analysis of high-silicon aluminium alloy indicated that high-hardness particles in soft parent metal had determinative function,including wearing resistance and supporting ability when wearing happened.Dents on soft parent metal surface produced by friction could store oil and were helpful for lubrication.The friction trace analysis showed that,high-hardness particles in high-silicon aluminium alloy could produce friction trace on 42MnCr52 steel surface,which proved friction function of high-hardness particles in high-silicon aluminium alloy.展开更多
Alloying of metals is known from antiquity. Alloy making <em>i.e.</em>, homogenizing metals started in a “hit-or-miss” way. The 1</span><sup><span style="font-family:Verdana;">...Alloying of metals is known from antiquity. Alloy making <em>i.e.</em>, homogenizing metals started in a “hit-or-miss” way. The 1</span><sup><span style="font-family:Verdana;">st</span></sup><span style="font-family:Verdana;"> alloy from copper (Cu) and tin (Sn) was produced around 2500 BC and from then Bronze Age began. Subsequently iron (Fe) age started after the Bronze Age. Aluminium (Al) alloying was discovered much later because pure Al could not be recovered easily even though Al is the most abundant metal in the earth’s crust. Refining of Al is a very difficult job because of its strong affinity towards oxygen. To ease alloying, melting points (mp) of the individual constituents and reactivity of metal towards oxygen were the hurdles. Now understanding the thermodynamics of metal mixing has paved alloying. Periodic properties of elements concerning size, electronegativity, crystal structure, valency, lattice spacing, etc. are considered for alloying. In this feature article, more emphasis is given to Hume-Rothery rules in which the necessary parameters for alloying have been illustrated. Importantly standard electrode potential (E</span><sup><span style="font-family:Verdana;">0</span></sup><span style="font-family:Verdana;">) values, eutectic, phase diagram, size-related strain in metals, etc. have been looked into in the present discussion. One elegant example is Sn-Pb alloy, known as soft solder. Soft solder was in use for many years to connect metals and in electric circuitry. Low melting, flowability, and conductivity of soft solder had placed Sn-Pb alloy a unique position in industries, laboratories and even in cottage industries. However, toxic Pb volatilizes during soldering and hence soft solder is banned almost in all countries. We felt the need for a viable alternative to obtain soldering material and then silver (Ag) based highly conducting, an eco-friendly alloy of Sn resulted in from a high boiling liquid. The discovery engenders not only a new conducting soldering alloy but also a new concept of melting metals together. Furthermore, new ideas of alloying have been generalized at their nanostages from a suitable high boiling solvent.展开更多
The preparation technique for a high silicon magnesium alloy ASE640 was explored. Different addition forms of silicon element to magnesium melt were compared and the master alloy method was selected. In addition, micr...The preparation technique for a high silicon magnesium alloy ASE640 was explored. Different addition forms of silicon element to magnesium melt were compared and the master alloy method was selected. In addition, microstructure and phase structure of this alloy were investigated with optical microscope, scan electronic microscope and X ray diffraction meter. The dissolution rate of Si in magnesium melt was discussed. It shows that the smaller the primary silicon strips in the master alloy are, the higher the dissolution rate and the less dissolution time are. The experimental results show that in as cast ASE640 alloy a lot of Mg 2Si intermetallic compound particles are found and they present the shape of Chinese characters. However, the mechanical properties at room temperature and creep properties at elevated temperature are decreased for the coarse Mg 2Si grains. The Mg 2Si grains can be refined by hot extrusion and dispersed uniformly in the matrix, which may efficiently improve the mechanical properties of the alloy.展开更多
基金Project(2007AA03Z557) supported by the National High-tech Research and Development Program of ChinaProject(50775086) supported by the National Natural Science Foundation of China
文摘The morphology changes of both Fe-containing intermetallic compounds and the primary Si phase of Al-20Si-2Fe-2Cu-0.4Mg-1.0Ni-0.5Mn (mass fraction, %) alloy produced by semi-solid rheo-diecasting were studied.The semi-solid slurry of high silicon aluminum alloy was prepared by direct ultrasonic vibration (DUV) which was imposed on the alloy near the liquidus temperature for about 2 min.Then, standard test samples of 6.4 mm in diameter were formed by semi-solid rheo-diecasting.The results show that the DUV treatment suppresses the formation of needle-like β-Al5(Fe,Mn)Si phase, and the Fe-containing intermetallic compounds exist in the form of fine Al4(Fe, Mn)Si2 particles.Additionally, the primary Si grows up as fine and round particles with uniform distribution in α(Al) matrix of this alloy under DUV treatment.The tensile strengths of the samples at the room temperature and 573 K are 230 MPa and 145 MPa, respectively.The coefficient of thermal expansion (CTE) between 25 °C and 300 °C is 16.052 8×10-6 °C-1, and the wear rate is 1.55%.The hardness of this alloy with 2% Fe reaches HB146.3.It is discovered that modified morphology and uniform distribution of the Fe-containing intermetallic compounds and the primary Si phase are the main reasons for reducing the CTE and increasing the wear resistance of this alloy.
基金supported by the National Natural Science Foundation of China(No.50974080)
文摘In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo) which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 oC to 400 oC. The impact toughness is 4-11 J?cm-2 at room temperature and the impact
文摘The P + Sr + Ce compound modification technologies of as-cast Al-21Si-1.5Cu-1.5Ni- 2.5Fe- 0.5Mg alloy were investigated by means of orthogonal test. Orthogonal test results show that 3% (CaH2PO4 + 2CASO4)+ 0.2%Sr + 0.2%Ce is the optimum additive of modification treatment which can fine eutectic and primary silicon also can change the form of rich-iron phase at same time. The needle form of rich-iron phase is Al9FeSi3, which is prored by X-ray diffraction analysis and X-ray energy spectrum analysis. After compound modification treatment, the needle form of rich-iron phase disappeared and the fish bone form of rich-iron and rich-Ce phase that is AlsCeFe emerged. Both at room temperature and at 300℃, the tensile strength of the alloy after the modification treatment with the optimum additive is 30% lager than that of the alloy unmodified. Observed by SEM, the brittle intercrystalline tensile fracture changed into a blended one in which has many dimples.
文摘A high Fe containing aluminum matrix filler metal for hardfacing aluminum silicon alloys has been developed by using iron,nickel,and silicon as the major strengthening elements,and by measuring mechanical properties,room temperature and high temperature wear tests,and microstructural analysis.The filler metal,which contains 3.0%-5.0% Fe and 11.0%-13.0% Si,exhibits an excellent weldability.The as cast and as welded microstructures for the filler metal are of uniformly distribution and its dispersed network of hard phase is enriched with Al Si Fe Ni.The filler metal shows high mechanical properties and wear resistance at both room temperature and high temperatures.The deposited metal has a better resistance to impact wear at 220℃ than that of substrate Al Si Mg Cu piston alloy;at room temperature,the deposited metal has an equivalent resistance to slide wear with lubrication as that of a hyper eutectic aluminum silicon alloy with 27% Si and 1% Ni.
文摘With tank special purpose lubricating oil,100N,200N and 800N loading force and different loading times,spray-formed high-silicon aluminium alloy and military superpower engine steel cylinder sleeve materials were used for comparative friction test and friction pair comparision test under simulated engine work condition.The results showed that,compared with steel cylinder sleeve materials,high-silicon aluminium alloy showed more excellent wearing resistance.The friction mechanism analysis of high-silicon aluminium alloy indicated that high-hardness particles in soft parent metal had determinative function,including wearing resistance and supporting ability when wearing happened.Dents on soft parent metal surface produced by friction could store oil and were helpful for lubrication.The friction trace analysis showed that,high-hardness particles in high-silicon aluminium alloy could produce friction trace on 42MnCr52 steel surface,which proved friction function of high-hardness particles in high-silicon aluminium alloy.
文摘Alloying of metals is known from antiquity. Alloy making <em>i.e.</em>, homogenizing metals started in a “hit-or-miss” way. The 1</span><sup><span style="font-family:Verdana;">st</span></sup><span style="font-family:Verdana;"> alloy from copper (Cu) and tin (Sn) was produced around 2500 BC and from then Bronze Age began. Subsequently iron (Fe) age started after the Bronze Age. Aluminium (Al) alloying was discovered much later because pure Al could not be recovered easily even though Al is the most abundant metal in the earth’s crust. Refining of Al is a very difficult job because of its strong affinity towards oxygen. To ease alloying, melting points (mp) of the individual constituents and reactivity of metal towards oxygen were the hurdles. Now understanding the thermodynamics of metal mixing has paved alloying. Periodic properties of elements concerning size, electronegativity, crystal structure, valency, lattice spacing, etc. are considered for alloying. In this feature article, more emphasis is given to Hume-Rothery rules in which the necessary parameters for alloying have been illustrated. Importantly standard electrode potential (E</span><sup><span style="font-family:Verdana;">0</span></sup><span style="font-family:Verdana;">) values, eutectic, phase diagram, size-related strain in metals, etc. have been looked into in the present discussion. One elegant example is Sn-Pb alloy, known as soft solder. Soft solder was in use for many years to connect metals and in electric circuitry. Low melting, flowability, and conductivity of soft solder had placed Sn-Pb alloy a unique position in industries, laboratories and even in cottage industries. However, toxic Pb volatilizes during soldering and hence soft solder is banned almost in all countries. We felt the need for a viable alternative to obtain soldering material and then silver (Ag) based highly conducting, an eco-friendly alloy of Sn resulted in from a high boiling liquid. The discovery engenders not only a new conducting soldering alloy but also a new concept of melting metals together. Furthermore, new ideas of alloying have been generalized at their nanostages from a suitable high boiling solvent.
文摘The preparation technique for a high silicon magnesium alloy ASE640 was explored. Different addition forms of silicon element to magnesium melt were compared and the master alloy method was selected. In addition, microstructure and phase structure of this alloy were investigated with optical microscope, scan electronic microscope and X ray diffraction meter. The dissolution rate of Si in magnesium melt was discussed. It shows that the smaller the primary silicon strips in the master alloy are, the higher the dissolution rate and the less dissolution time are. The experimental results show that in as cast ASE640 alloy a lot of Mg 2Si intermetallic compound particles are found and they present the shape of Chinese characters. However, the mechanical properties at room temperature and creep properties at elevated temperature are decreased for the coarse Mg 2Si grains. The Mg 2Si grains can be refined by hot extrusion and dispersed uniformly in the matrix, which may efficiently improve the mechanical properties of the alloy.