The effects of Zn content on strength and wear performance of Al-12Si-3 Cu alloy synthesized by gravity casting were systematically investigated.The microstructure and mechanical properties of the alloys were evaluate...The effects of Zn content on strength and wear performance of Al-12Si-3 Cu alloy synthesized by gravity casting were systematically investigated.The microstructure and mechanical properties of the alloys were evaluated using OM,XRD,SEM as well as hardness,tension,compression and Charpy impact tests.Their dry sliding wear tests were carried out with a ball-on-disk tester.Microscopic examinations revealed that the microstructure of the base alloy consisted of theα(Al)dendrites,needle-type and coarse Si particles,and CuAl2(θ)phase.The addition of Zn to this alloy resulted in the formation ofα-solid solution phase and the increase of coarse Si particles.The hardness,yield,tensile and compressive strengths,elongation to fracture and impact toughness of the Al-12Si-3 Cu-Zn alloys increased with increasing Zn content,but tendency in the tensile and compressive strengths and ductility reversed after adding 1.5%-2%Zn.In addition,the friction coefficient and volume loss of the Al-12Si-3 Cu-Zn alloys decreased with increasing Zn content.The study showed that the addition of Zn to Al-12Si-3 Cu alloy can improve its potential applications as tribological material.展开更多
The effects of Cu content on the microstructure and mechanical properties of thixoformed Al-6Si-xCu-0.3Mg(x= 3,4,5and 6,mass fraction,%) alloys were studied.The samples were thixoformed at 50%liquid content and severa...The effects of Cu content on the microstructure and mechanical properties of thixoformed Al-6Si-xCu-0.3Mg(x= 3,4,5and 6,mass fraction,%) alloys were studied.The samples were thixoformed at 50%liquid content and several of the samples were treated with the T6 heat treatment.The samples were then examined by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX) spectroscopy and X-ray diffraction(XRD) analysis,as well as hardness and tensile tests.The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting.The results also reveal that as the Cu content in the alloy increases,the hardness and tensile strength of the thixoformed alloys also increase.The ultimate tensile strength,yield strength and elongation to fracture of the thixoformed heat-treated Al-6Si-3Cu-0.3Mg alloy are 298 MPa,201 MPa and 4.5%,respectively,whereas the values of the thixoformed heat-treated alloy with high Cu content(6%) are 361 MPa,274 MPa and 1.1%,respectively.The fracture of the thixoformed Al-6Si-3Cu-0.3Mg alloy shows a dimple rupture,whereas in the alloy that contains the highest Cu content(6%),a cleavage fracture is observed.展开更多
The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure,mechanical and tribological properties of the Al-Si-Cu-Mg alloys.In this context,a series of Al-12Si...The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure,mechanical and tribological properties of the Al-Si-Cu-Mg alloys.In this context,a series of Al-12Si-3Cu-(0.5-2.5)Mg(wt.%)alloys were produced by permanent mould casting,and then subjected to T6 treatment.Their microstructure and mechanical properties were investigated using OM,XRD,SEM,EDS along with hardness,tension,compression and Charpy impact tests.Dry sliding friction and wear properties of the alloys were studied using a ball-on-disk type tester.It was observed that the microstructure of as-cast Al-12Si-3 Cu-Mg alloys consisted of a(Al),Si,O-CuAb,0-Mg_(2)Si,0-AbMg_(8)Cu(2)Si_(6) and π-AhMg_(3)FeSi_(6) phases.T6 heat treatment gave rise to nearly spherodization of eutectic Si particles,formation of finer 0-CuAH and 0-Mg_(2)Si precipitates and elimination of Chinese script morphology of 0-Mg_(2)Si phase.The addition of Mg up to 2.5 wt.%decreased the hardness,tensile and compressive strengths,tensile elongation and impact toughness of the as-cast and T6-treated alloys and increased their friction coefficient and volume loss.T6 treatment,on the other hand,led to a significant increase in mechanical properties and wear resistance of as-cast alloys.展开更多
In the present work, scandium elements with a series of contents(0.06 wt.%, 0.10 wt.%, 0.14 wt.%,0.17 wt.%, 0.20 wt.% and 0.25 wt.%) were added in a high Zn-containing Al-Zn-Mg-Cu-Zr alloy and the corresponding as-cas...In the present work, scandium elements with a series of contents(0.06 wt.%, 0.10 wt.%, 0.14 wt.%,0.17 wt.%, 0.20 wt.% and 0.25 wt.%) were added in a high Zn-containing Al-Zn-Mg-Cu-Zr alloy and the corresponding as-cast microstructure characteristics including grains and phases were thoroughly investigated. The results indicated that fine grain boundaries existed in these alloys and fine MgZn2phases discontinuously distributed on them. Besides,AlZnMgCu eutectic phases and Sc, Zr-containing phases with flocculent morphology were observed. As scandium contents vary from 0.06 wt.% to 0.17 wt.%, the average grain size continuously decreased and its equiaxial characteristics were strengthened. Meanwhile, the content of AlZnMgCu eutectic phase showed a decrease trend. When scandium contents were 0.20 wt.% and 0.25 wt.%, no further enhancement on grain refinement was observed, so as to the reduction of AlZnMgCu eutectic phase content. Besides, Sc, Zr-containing phases with blocky morphology were observed and the alloy with a scandium content of 0.25 wt.% possessed a larger amount of blocky Sc, Zr-containing phase than the alloy with a scandium content of 0.20 wt.%. Grain refinement and reduction of AlZnMgCu eutectic phase content associated with scandium addition were discussed.展开更多
文摘The effects of Zn content on strength and wear performance of Al-12Si-3 Cu alloy synthesized by gravity casting were systematically investigated.The microstructure and mechanical properties of the alloys were evaluated using OM,XRD,SEM as well as hardness,tension,compression and Charpy impact tests.Their dry sliding wear tests were carried out with a ball-on-disk tester.Microscopic examinations revealed that the microstructure of the base alloy consisted of theα(Al)dendrites,needle-type and coarse Si particles,and CuAl2(θ)phase.The addition of Zn to this alloy resulted in the formation ofα-solid solution phase and the increase of coarse Si particles.The hardness,yield,tensile and compressive strengths,elongation to fracture and impact toughness of the Al-12Si-3 Cu-Zn alloys increased with increasing Zn content,but tendency in the tensile and compressive strengths and ductility reversed after adding 1.5%-2%Zn.In addition,the friction coefficient and volume loss of the Al-12Si-3 Cu-Zn alloys decreased with increasing Zn content.The study showed that the addition of Zn to Al-12Si-3 Cu alloy can improve its potential applications as tribological material.
基金Universiti Teknikal Malaysia Melaka (UTeM) and the Ministry of Education Malaysia for financial support of this studyUniversiti Kebangsaan Malaysia (UKM) for the financial support under research grants GUP-2012-040 and AP-2012-014
文摘The effects of Cu content on the microstructure and mechanical properties of thixoformed Al-6Si-xCu-0.3Mg(x= 3,4,5and 6,mass fraction,%) alloys were studied.The samples were thixoformed at 50%liquid content and several of the samples were treated with the T6 heat treatment.The samples were then examined by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray(EDX) spectroscopy and X-ray diffraction(XRD) analysis,as well as hardness and tensile tests.The results show that the cooling slope casting and thixoforming process promote the formation of very fine and well distributed intermetallic compounds in the aluminium matrix and the mechanical properties of the alloys increase considerably compared with the permanent mould casting.The results also reveal that as the Cu content in the alloy increases,the hardness and tensile strength of the thixoformed alloys also increase.The ultimate tensile strength,yield strength and elongation to fracture of the thixoformed heat-treated Al-6Si-3Cu-0.3Mg alloy are 298 MPa,201 MPa and 4.5%,respectively,whereas the values of the thixoformed heat-treated alloy with high Cu content(6%) are 361 MPa,274 MPa and 1.1%,respectively.The fracture of the thixoformed Al-6Si-3Cu-0.3Mg alloy shows a dimple rupture,whereas in the alloy that contains the highest Cu content(6%),a cleavage fracture is observed.
文摘The aim of the present study was to investigate the influence of Mg addition and T6 heat treatment on microstructure,mechanical and tribological properties of the Al-Si-Cu-Mg alloys.In this context,a series of Al-12Si-3Cu-(0.5-2.5)Mg(wt.%)alloys were produced by permanent mould casting,and then subjected to T6 treatment.Their microstructure and mechanical properties were investigated using OM,XRD,SEM,EDS along with hardness,tension,compression and Charpy impact tests.Dry sliding friction and wear properties of the alloys were studied using a ball-on-disk type tester.It was observed that the microstructure of as-cast Al-12Si-3 Cu-Mg alloys consisted of a(Al),Si,O-CuAb,0-Mg_(2)Si,0-AbMg_(8)Cu(2)Si_(6) and π-AhMg_(3)FeSi_(6) phases.T6 heat treatment gave rise to nearly spherodization of eutectic Si particles,formation of finer 0-CuAH and 0-Mg_(2)Si precipitates and elimination of Chinese script morphology of 0-Mg_(2)Si phase.The addition of Mg up to 2.5 wt.%decreased the hardness,tensile and compressive strengths,tensile elongation and impact toughness of the as-cast and T6-treated alloys and increased their friction coefficient and volume loss.T6 treatment,on the other hand,led to a significant increase in mechanical properties and wear resistance of as-cast alloys.
基金Projects(2020YFB0311400ZL, 2020YFF0218202) supported by the National Key R&D Program of ChinaProject supported by Youth Fund Project of GRINM Group Co.,Ltd.,China。
文摘In the present work, scandium elements with a series of contents(0.06 wt.%, 0.10 wt.%, 0.14 wt.%,0.17 wt.%, 0.20 wt.% and 0.25 wt.%) were added in a high Zn-containing Al-Zn-Mg-Cu-Zr alloy and the corresponding as-cast microstructure characteristics including grains and phases were thoroughly investigated. The results indicated that fine grain boundaries existed in these alloys and fine MgZn2phases discontinuously distributed on them. Besides,AlZnMgCu eutectic phases and Sc, Zr-containing phases with flocculent morphology were observed. As scandium contents vary from 0.06 wt.% to 0.17 wt.%, the average grain size continuously decreased and its equiaxial characteristics were strengthened. Meanwhile, the content of AlZnMgCu eutectic phase showed a decrease trend. When scandium contents were 0.20 wt.% and 0.25 wt.%, no further enhancement on grain refinement was observed, so as to the reduction of AlZnMgCu eutectic phase content. Besides, Sc, Zr-containing phases with blocky morphology were observed and the alloy with a scandium content of 0.25 wt.% possessed a larger amount of blocky Sc, Zr-containing phase than the alloy with a scandium content of 0.20 wt.%. Grain refinement and reduction of AlZnMgCu eutectic phase content associated with scandium addition were discussed.
