The aging-hardening kinetics of powder metallurgy processed 2014Al alloy and its composite have been studied. The existence of n-SiC particulates leads to the increase of peak hardness. Interestingly, the aginghardeni...The aging-hardening kinetics of powder metallurgy processed 2014Al alloy and its composite have been studied. The existence of n-SiC particulates leads to the increase of peak hardness. Interestingly, the aginghardening peak of the composite takes place at earlier time than that of the unreinforced alloy. Transmission electron microscopy（TEM） studies indicated that the major precipitation phases are Al_5Cu_2Mn_3 and θ′（Al_2Cu）. Besides, Ω phase appeared in both specimens at peak hardening condition, which has been rarely observed previously in aluminum metal matrix composites without Ag. Accelerated aging kinetics and increased peak hardness may be attributed to the higher dislocation density resulted from the mismatch of coefficients of thermal expansion between n-SiC and 2014Al matrix. The results are beneficial to fabricating high performance composites for the application in automobile field such as pistons, driveshaft tubes, brake rotors, bicycle frames, railroad brakes.展开更多
Spherical carbamide particles were employed to produce porous Fe–Cr–C alloy with high porosity and large aperture via the space-holder leaching technique. A series of porous samples were prepared by regulating the p...Spherical carbamide particles were employed to produce porous Fe–Cr–C alloy with high porosity and large aperture via the space-holder leaching technique. A series of porous samples were prepared by regulating the processing parameters, which included the carbamide content and the compaction pressure. The pore characteristics and compression properties of the produced samples were investigated. The samples were characterized by scanning electron microscopy, image analysis, and compression tests. The results showed that the macro-porosity and the mean pore size were in the ranges 40.4%–82.4% and 0.6–1.5 mm, respectively. The compressive strength varied between 25.38 MPa and 127.9 MPa, and was observed to decrease with increasing total porosity.展开更多
In order to understand the influence of nano-sized B4C additive on ZA27 alloy, mechanical and physical properties of ZA27-B4C nanocomposites were investigated in terms of B4C content. While physical properties were de...In order to understand the influence of nano-sized B4C additive on ZA27 alloy, mechanical and physical properties of ZA27-B4C nanocomposites were investigated in terms of B4C content. While physical properties were determined in terms of microstructural studies, density and porosity tests, mechanical properties were determined in terms of ultimate tensile strength（UTS） and hardness experiments. Morphological and microstructural studies were carried out with scanning electron microscopy（SEM）. The experimental results indicate that nano-sized B4C can be used to enhance the mechanical properties of ZA27 alloy effectively. The highest mechanical performance can be obtained at ZA27-0.5% B4C（in weight） nanocomposite with values of tensile strength（247 MPa） and hardness（141,18 BH） and low partial porosity（0.5%）. After a pick point, increasing B4C ratio may cause the formation of agglomeration in grain boundaries, that＇s why density, tensile strength, and hardness values are declined.展开更多
基金Financial support by the National Basic Research Program of China(“973”Program,No.2012CB619600)the National Natural Science Foundation of China(No.51474111)+2 种基金the Science and Technology Development Project of Jilin Province(No.20160519002JH)support came from the Fundamental Research Funds for the Central Universities(JCKY-QKJC02)the Chang Bai Mountain Scholars Program(2013014)
文摘The aging-hardening kinetics of powder metallurgy processed 2014Al alloy and its composite have been studied. The existence of n-SiC particulates leads to the increase of peak hardness. Interestingly, the aginghardening peak of the composite takes place at earlier time than that of the unreinforced alloy. Transmission electron microscopy（TEM） studies indicated that the major precipitation phases are Al_5Cu_2Mn_3 and θ′（Al_2Cu）. Besides, Ω phase appeared in both specimens at peak hardening condition, which has been rarely observed previously in aluminum metal matrix composites without Ag. Accelerated aging kinetics and increased peak hardness may be attributed to the higher dislocation density resulted from the mismatch of coefficients of thermal expansion between n-SiC and 2014Al matrix. The results are beneficial to fabricating high performance composites for the application in automobile field such as pistons, driveshaft tubes, brake rotors, bicycle frames, railroad brakes.
基金financially supported by the Shaanxi Province Science and Technology Innovation Project Plan(No.2012KTCL01-08)
文摘Spherical carbamide particles were employed to produce porous Fe–Cr–C alloy with high porosity and large aperture via the space-holder leaching technique. A series of porous samples were prepared by regulating the processing parameters, which included the carbamide content and the compaction pressure. The pore characteristics and compression properties of the produced samples were investigated. The samples were characterized by scanning electron microscopy, image analysis, and compression tests. The results showed that the macro-porosity and the mean pore size were in the ranges 40.4%–82.4% and 0.6–1.5 mm, respectively. The compressive strength varied between 25.38 MPa and 127.9 MPa, and was observed to decrease with increasing total porosity.
基金Funded by the Research Projects Unit of Karadeniz Technical(Number:12040)TUBITAK(Number:213M276)
文摘In order to understand the influence of nano-sized B4C additive on ZA27 alloy, mechanical and physical properties of ZA27-B4C nanocomposites were investigated in terms of B4C content. While physical properties were determined in terms of microstructural studies, density and porosity tests, mechanical properties were determined in terms of ultimate tensile strength（UTS） and hardness experiments. Morphological and microstructural studies were carried out with scanning electron microscopy（SEM）. The experimental results indicate that nano-sized B4C can be used to enhance the mechanical properties of ZA27 alloy effectively. The highest mechanical performance can be obtained at ZA27-0.5% B4C（in weight） nanocomposite with values of tensile strength（247 MPa） and hardness（141,18 BH） and low partial porosity（0.5%）. After a pick point, increasing B4C ratio may cause the formation of agglomeration in grain boundaries, that＇s why density, tensile strength, and hardness values are declined.
