A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the rel...A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature,interfacial microstructure and joint strength were emphatically investigated.Results show that the TiAl joints brazed at 1160 and 1180℃ possess three interfacial layers and mainly consist of α_(2)-Ti_(3)Al,τ_(3)-Al_(3)NiTi_(2) and Ti_(2)Ni,but the brazing seams are no longer layered and Ti_(2)Ni is completely replaced by the uniformly distributed τ_(3)-Al_(3)NiTi_(2) at 1200 and 1220℃ due to the destruction of α_(2)-Ti_(3)Al barrier layer.This transformation at 1200℃ obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa.Notably,the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.展开更多
The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys（x = 0,0.01,…,0.09 and 0.1,mole fraction） were investigated.The AlCoCrFeNi high entropy alloy exh...The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys（x = 0,0.01,…,0.09 and 0.1,mole fraction） were investigated.The AlCoCrFeNi high entropy alloy exhibits equiaxed grain structures with obvious composition segregation.However,with the addition of B element,the alloys exhibit dendrite structures.Inside the dendrites,spinodal decomposition structure can be clearly observed.With the addition of B element,the crystal structures change from（B2 ＋ BCC） to（B2 ＋ BCC ＋ FCC） structures,and the hardness firstly increases from HV 486.7 to HV 502.4,then declines to HV 460.7（x ≥ 0.02）.The compressive fracture strength firstly shows a trend of increasing,and then declining（x ≥ 0.08）.The coercive forces and the specific saturation magnetizations of the alloys decrease as B addition contents increase,the decreasing coercive forces show a better soft magnetic behavior.展开更多
Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properti...Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properties were investigated. Results showed that the tensile strength and elongation of the SSSC-fabricated rod were improved by 22% and 17%, respectively, compared with those of the LSC-fabricated rod. For SSSC, the average particle size（APS） and the shape factor（SF） increased with the increase of re-melting temperature（Tr）, whereas the tensile strength and elongation increased first and then decreased. The APS increased with increasing the mold temperature（Tm）, whereas the SF increased initially and then decreased, which caused the tensile strength and elongation to increase initially and then decrease. The APS decreased and the SF increased as squeezing pressure（ps） increased, and the mechanical properties were enhanced. Moreover, the optimal Tr, ps and Tm are 848 K, 100 MPa and 523 K, respectively.展开更多
The as-cast microstructure of AE42 was of typical dendritic and composed of the a matrix and some needle-shaped interphases Al11RE3. A small mount of Ca addition results in significant microstructural refinement and f...The as-cast microstructure of AE42 was of typical dendritic and composed of the a matrix and some needle-shaped interphases Al11RE3. A small mount of Ca addition results in significant microstructural refinement and formation of a Al2Ca phase, which showed two kinds of morphologies, lamellar and tiny granular. The former distributes on grain boundaries and the later is within the matrix grains. With the increase of Ca addition the volume fraction of Al-RE compound (Al11RE3) decreases, but Al2Ca increases. Addition of Ca causes a significant increase of yield strength of the alloy both at ambient and elevated temperatures, but a little decrease of the ductility. With calcium addition the ultimate strength decreases at ambient temperature and 150°t, but increases at 175°C and 200°C.展开更多
Based on the Mg58.5Cu30.5Y11 alloy, 10% Ti, 10% Be and 10% Ti70Be30 （mole fraction） were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. Th...Based on the Mg58.5Cu30.5Y11 alloy, 10% Ti, 10% Be and 10% Ti70Be30 （mole fraction） were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. The phase constituent, thermal stability and microstructure of the alloys were investigated by using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy, respectively. The effects of alloying elements Ti and Be on the microstructure and mechanical properties of Mg58.sCu3o.sYll alloy were discussed. The results show that CuTi phase is distributed in （Mg0.585Cu0.305Y0.11）90Ti10 and （Mg58.5Cu30.5Y11）90（Ti0.7Be0.3）10 alloys, while CuYBe glassy phase containing CuY crystals is embedded in the matrix of （Mg58.5Cu30.5Y11）90Be10 alloy. Under uniaxial compressive loading, the largest compressive fracture strengths for （Mg58.5Cu30.5Y11）90Ti10, （Mg58.5Cu30.5Y11）90Be10 and （Mg58.5Cu30.5Y11）90（Ti0.7Be0.3）10 alloys are 797.6, 952.6 and 1007.8 MPa, respectively, and the strengths are increased by about 17%, 40% and 48% compared with Mg58.5Cu30.5Y11 alloy. The strength reliability for the three alloys is much improved according to the strength distribution region of 10 samples of each alloy.展开更多
A series of Al?Si?Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al?Si?G...A series of Al?Si?Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al?Si?Ge filler metals drops from 592 to 519 °C as the content of Ge increases from 0 to 30% (mass fraction). As the content of Ge increases, bright eutectic Ge forms. However, as the Ge content exceeds 20%, the aggregation growth of the eutectic structure tends to happen and coarsened primary Si?Ge particle forms, which is detrimental to the properties of alloys. The Al?10.8Si?10Ge filler metal has good processability and wettability with the base metal Al. When this filler metal is used to braze 1060 aluminum, the complete joint can be achieved. Furthermore, the shear strength test results show that the fracture of brazed joint with Al?10.8Si?10Ge filler metal occurs in the base metal.展开更多
The microstructure and properties of TZP ceramics fabricated from spray dried powder differing in granule morphology and deformability are determined.The effects of the feed slurry solids con...The microstructure and properties of TZP ceramics fabricated from spray dried powder differing in granule morphology and deformability are determined.The effects of the feed slurry solids content on the granule character are discussed.The lower solid content results in hard and tough ‘donut’ shaped granules that resist deformation during compaction.The microphotograph shows that relatively large intergranular pores formed by incomplete deformation of granules persist during sintering and are the major strength limiting defects in fired material.Sintered material produced from uniform and deformable granules has a homogeneous microstructure and relatively high mean strength.展开更多
基金the National Natural Science Foundation of China(No.51865012)the Natural Science Foundation of Jiangxi Province,China(No.20202BABL204040)+3 种基金the Open Foundation of National Engineering Research Center of Near-net-shape Forming for Metallic Materials,China(No.2016005)the Science Foundation of Educational Department of Jiangxi Province,China(No.GJJ170372)the GF Basic Scientific Research Project,China(No.JCKY2020205C002)the Civil Population Supporting Planning and Development Project,China(No.JPPT125GH038).
文摘A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature,interfacial microstructure and joint strength were emphatically investigated.Results show that the TiAl joints brazed at 1160 and 1180℃ possess three interfacial layers and mainly consist of α_(2)-Ti_(3)Al,τ_(3)-Al_(3)NiTi_(2) and Ti_(2)Ni,but the brazing seams are no longer layered and Ti_(2)Ni is completely replaced by the uniformly distributed τ_(3)-Al_(3)NiTi_(2) at 1200 and 1220℃ due to the destruction of α_(2)-Ti_(3)Al barrier layer.This transformation at 1200℃ obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa.Notably,the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.
基金Projects(51134013,51104029,51471044)supported by the National Natural Science Foundation of ChinaProject supported by the Fundamental Research Funds for the Central Universities,China+1 种基金Project(LZ2014007)supported by the Key Laboratory of Basic Research Projects of Liaoning Province Department of Education,ChinaProject(2014028013)supported by the Natural Science Foundation of Liaoning Province,China
文摘The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys（x = 0,0.01,…,0.09 and 0.1,mole fraction） were investigated.The AlCoCrFeNi high entropy alloy exhibits equiaxed grain structures with obvious composition segregation.However,with the addition of B element,the alloys exhibit dendrite structures.Inside the dendrites,spinodal decomposition structure can be clearly observed.With the addition of B element,the crystal structures change from（B2 ＋ BCC） to（B2 ＋ BCC ＋ FCC） structures,and the hardness firstly increases from HV 486.7 to HV 502.4,then declines to HV 460.7（x ≥ 0.02）.The compressive fracture strength firstly shows a trend of increasing,and then declining（x ≥ 0.08）.The coercive forces and the specific saturation magnetizations of the alloys decrease as B addition contents increase,the decreasing coercive forces show a better soft magnetic behavior.
基金Project(51335009)supported by the National Natural Science Foundation of ChinaProject(2014JQ7273)supported by the Natural Science Foundation of Shaanxi Province of ChinaProject(CXY1514(1))supported by the Xi’an Science and Technology Plan Projects,China
文摘Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properties were investigated. Results showed that the tensile strength and elongation of the SSSC-fabricated rod were improved by 22% and 17%, respectively, compared with those of the LSC-fabricated rod. For SSSC, the average particle size（APS） and the shape factor（SF） increased with the increase of re-melting temperature（Tr）, whereas the tensile strength and elongation increased first and then decreased. The APS increased with increasing the mold temperature（Tm）, whereas the SF increased initially and then decreased, which caused the tensile strength and elongation to increase initially and then decrease. The APS decreased and the SF increased as squeezing pressure（ps） increased, and the mechanical properties were enhanced. Moreover, the optimal Tr, ps and Tm are 848 K, 100 MPa and 523 K, respectively.
文摘The as-cast microstructure of AE42 was of typical dendritic and composed of the a matrix and some needle-shaped interphases Al11RE3. A small mount of Ca addition results in significant microstructural refinement and formation of a Al2Ca phase, which showed two kinds of morphologies, lamellar and tiny granular. The former distributes on grain boundaries and the later is within the matrix grains. With the increase of Ca addition the volume fraction of Al-RE compound (Al11RE3) decreases, but Al2Ca increases. Addition of Ca causes a significant increase of yield strength of the alloy both at ambient and elevated temperatures, but a little decrease of the ductility. With calcium addition the ultimate strength decreases at ambient temperature and 150°t, but increases at 175°C and 200°C.
基金Project(2011CB606301)supported by the National Basic Research Program of China
文摘Based on the Mg58.5Cu30.5Y11 alloy, 10% Ti, 10% Be and 10% Ti70Be30 （mole fraction） were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. The phase constituent, thermal stability and microstructure of the alloys were investigated by using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy, respectively. The effects of alloying elements Ti and Be on the microstructure and mechanical properties of Mg58.sCu3o.sYll alloy were discussed. The results show that CuTi phase is distributed in （Mg0.585Cu0.305Y0.11）90Ti10 and （Mg58.5Cu30.5Y11）90（Ti0.7Be0.3）10 alloys, while CuYBe glassy phase containing CuY crystals is embedded in the matrix of （Mg58.5Cu30.5Y11）90Be10 alloy. Under uniaxial compressive loading, the largest compressive fracture strengths for （Mg58.5Cu30.5Y11）90Ti10, （Mg58.5Cu30.5Y11）90Be10 and （Mg58.5Cu30.5Y11）90（Ti0.7Be0.3）10 alloys are 797.6, 952.6 and 1007.8 MPa, respectively, and the strengths are increased by about 17%, 40% and 48% compared with Mg58.5Cu30.5Y11 alloy. The strength reliability for the three alloys is much improved according to the strength distribution region of 10 samples of each alloy.
基金Project(2010A080402014)supported by the Guangdong Provincial Science and Technology Foundation,China
文摘A series of Al?Si?Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al?Si?Ge filler metals drops from 592 to 519 °C as the content of Ge increases from 0 to 30% (mass fraction). As the content of Ge increases, bright eutectic Ge forms. However, as the Ge content exceeds 20%, the aggregation growth of the eutectic structure tends to happen and coarsened primary Si?Ge particle forms, which is detrimental to the properties of alloys. The Al?10.8Si?10Ge filler metal has good processability and wettability with the base metal Al. When this filler metal is used to braze 1060 aluminum, the complete joint can be achieved. Furthermore, the shear strength test results show that the fracture of brazed joint with Al?10.8Si?10Ge filler metal occurs in the base metal.
文摘The microstructure and properties of TZP ceramics fabricated from spray dried powder differing in granule morphology and deformability are determined.The effects of the feed slurry solids content on the granule character are discussed.The lower solid content results in hard and tough ‘donut’ shaped granules that resist deformation during compaction.The microphotograph shows that relatively large intergranular pores formed by incomplete deformation of granules persist during sintering and are the major strength limiting defects in fired material.Sintered material produced from uniform and deformable granules has a homogeneous microstructure and relatively high mean strength.
