Resin-bonded Al-SiC composite was sintered at 1100,1300,and 1500℃ in the air,the oxidation mechanism was investigated.The reaction models were also established.The oxidation resistance of the Al-SiC composite was sig...Resin-bonded Al-SiC composite was sintered at 1100,1300,and 1500℃ in the air,the oxidation mechanism was investigated.The reaction models were also established.The oxidation resistance of the Al-SiC composite was significantly enhanced with temperature increase.SiC in the exterior of the composite was partially oxidized slightly,while the transformation of metastable Al_(4)C_(3) to stable Al_(4)SiC_(4) existed in the interior.At 1100℃,Al in the interior reacted with residual C to form Al_(4)C_(3).With increasing to 1300℃,high temperature and low oxygen partial pressure lead to active oxidation of SiC,and internal gas composition transforms to Al_(2)O(g)+CO(g)+SiO(g)as the reaction proceeds.After Al_(4)C_(3) is formed,CO(g)and SiO(g)are continuously deposited on its surface,transforming to Al_(4)SiC_(4).At 1500℃,a dense layer consisting of SiC and Al_(4)SiC_(4) whiskers is formed which cuts off the diffusion channel of oxygen.The active oxidation of SiC is accelerated,enabling more gas to participate in the synthesis of Al_(4)SiC_(4),eventually forming hexagonal lamellar Al_(4)SiC_(4) with mutual accumulation between SiC particles.Introducing Al enhances the oxidation resistance of SiC.In addition,the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.展开更多
icrostructure and mechanical properties of Al_4C_3 and Al_2O_3 dispersion strengthened aluminum composite fabricated by mechanical attrition and hotpressing consolidation method were studied. It was shown that fine we...icrostructure and mechanical properties of Al_4C_3 and Al_2O_3 dispersion strengthened aluminum composite fabricated by mechanical attrition and hotpressing consolidation method were studied. It was shown that fine well developed Al_4C_3 stick and equiaxed γAl_2O_3 dispersoids with total content of about 6.6 v% uniformly distributed within the Al grains or along the grain boundaries. The Al/Al_4C_3 and Al/Al_2O_3 interfaces are very clean and well bonded at atomic level, but have no fixed orientation relationships between the dispersoids and the aluminum matrix exists. At ambient and especially elevated temperatures, strength and stiffness of the composite are much higher than that of P/M Al and even better than that of the 15 v% SiCw/Al composite.展开更多
The microstructure and tensile properties of Al_4C_3 dispersion strengthened Al composite fabricated by reaction milling technique were investigated.It is indicated that the rod-like Al_4C_3 dispersoids having a diame...The microstructure and tensile properties of Al_4C_3 dispersion strengthened Al composite fabricated by reaction milling technique were investigated.It is indicated that the rod-like Al_4C_3 dispersoids having a diameter of 0.02-0.03 μm and a length of 0.1-0.3μm are formed by reaction of C with Al, and uniformly distributed in the Al matrix.The interface between Al_4C_3 and Al is clean and the interfacial bonding is good.The matrix consists of the subgrains which have the size of 0.3-0.4μm, and most of the Al_4C_3 dispersoids are distributed on the subgrain boundaries.The 11 vol.-% Al_4C_3/Al composite exhibits an UTS (ultimate tensile strength) of 400 MPa and an elongation-to-failure of 8.0%.展开更多
Crystal structure of Ti_(5)Al_(2)C_(3)was determined by means of X-ray powder diffraction(XRPD),transmission electron microscopy(TEM)and ab initio calculations.In contrast to the already known P63/mmc space group that...Crystal structure of Ti_(5)Al_(2)C_(3)was determined by means of X-ray powder diffraction(XRPD),transmission electron microscopy(TEM)and ab initio calculations.In contrast to the already known P63/mmc space group that the MAX phases crystallize,it was demonstrated that the R3_m space group could better satisfy the experimental data.The lattice parameters are a=0.30564 nm,c=4.81846 nm in a hexagonal unit cell.展开更多
In this work,bulk Zr_(3)Al_(3)C_(5)-based ceramics were synthesized by the infiltration of A1-Si melt into zirconium carbide (ZrC) perform.The phase composition,microstructure,and mechanical properties of as-fabricate...In this work,bulk Zr_(3)Al_(3)C_(5)-based ceramics were synthesized by the infiltration of A1-Si melt into zirconium carbide (ZrC) perform.The phase composition,microstructure,and mechanical properties of as-fabricated ceramics were studied.The results demonstrate that Si is more effective to reduce the twin boundary energy of ZrC than A1,and thus promotes the decrease of formation temperature of Zr_(3)Al_(3)C_(5).With the infiltration temperatures increasing from 1200 to 1500 ℃,the Zr_(3)Al_(3)C_(5) content increases from 10 to 49 vol%,which is contributed to the increase of flexural strength from 62±9 to 222±10 MPa,and fracture toughness (KIC) from 2.8+0.2 to 4.1±0.3 MPa.m^(1/2).The decrease of mechanical properties for the samples fabricated at 1600 ℃ is ascribed to the abnormal growth of Zr_(3)Al_(3)C_(5) grains.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB3701400).
文摘Resin-bonded Al-SiC composite was sintered at 1100,1300,and 1500℃ in the air,the oxidation mechanism was investigated.The reaction models were also established.The oxidation resistance of the Al-SiC composite was significantly enhanced with temperature increase.SiC in the exterior of the composite was partially oxidized slightly,while the transformation of metastable Al_(4)C_(3) to stable Al_(4)SiC_(4) existed in the interior.At 1100℃,Al in the interior reacted with residual C to form Al_(4)C_(3).With increasing to 1300℃,high temperature and low oxygen partial pressure lead to active oxidation of SiC,and internal gas composition transforms to Al_(2)O(g)+CO(g)+SiO(g)as the reaction proceeds.After Al_(4)C_(3) is formed,CO(g)and SiO(g)are continuously deposited on its surface,transforming to Al_(4)SiC_(4).At 1500℃,a dense layer consisting of SiC and Al_(4)SiC_(4) whiskers is formed which cuts off the diffusion channel of oxygen.The active oxidation of SiC is accelerated,enabling more gas to participate in the synthesis of Al_(4)SiC_(4),eventually forming hexagonal lamellar Al_(4)SiC_(4) with mutual accumulation between SiC particles.Introducing Al enhances the oxidation resistance of SiC.In addition,the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.
文摘icrostructure and mechanical properties of Al_4C_3 and Al_2O_3 dispersion strengthened aluminum composite fabricated by mechanical attrition and hotpressing consolidation method were studied. It was shown that fine well developed Al_4C_3 stick and equiaxed γAl_2O_3 dispersoids with total content of about 6.6 v% uniformly distributed within the Al grains or along the grain boundaries. The Al/Al_4C_3 and Al/Al_2O_3 interfaces are very clean and well bonded at atomic level, but have no fixed orientation relationships between the dispersoids and the aluminum matrix exists. At ambient and especially elevated temperatures, strength and stiffness of the composite are much higher than that of P/M Al and even better than that of the 15 v% SiCw/Al composite.
基金National Natural Science Foundation of China(51873146)Ningbo Municipal Natural Science Foundation(2018A610005)+1 种基金Major Project of the Ministry of Science and Technology of China(2015ZX06004-001)Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University(Faculty Grant SFO-Mat-LiU No.200900971)。
文摘The microstructure and tensile properties of Al_4C_3 dispersion strengthened Al composite fabricated by reaction milling technique were investigated.It is indicated that the rod-like Al_4C_3 dispersoids having a diameter of 0.02-0.03 μm and a length of 0.1-0.3μm are formed by reaction of C with Al, and uniformly distributed in the Al matrix.The interface between Al_4C_3 and Al is clean and the interfacial bonding is good.The matrix consists of the subgrains which have the size of 0.3-0.4μm, and most of the Al_4C_3 dispersoids are distributed on the subgrain boundaries.The 11 vol.-% Al_4C_3/Al composite exhibits an UTS (ultimate tensile strength) of 400 MPa and an elongation-to-failure of 8.0%.
基金This work was funded by the NSFC under Grant No.50832008,Grant No.91226202 and the IMR innovative research foundation.
文摘Crystal structure of Ti_(5)Al_(2)C_(3)was determined by means of X-ray powder diffraction(XRPD),transmission electron microscopy(TEM)and ab initio calculations.In contrast to the already known P63/mmc space group that the MAX phases crystallize,it was demonstrated that the R3_m space group could better satisfy the experimental data.The lattice parameters are a=0.30564 nm,c=4.81846 nm in a hexagonal unit cell.
基金This work was supported by the National Natural Science Foundation of China(Nos.51702261,52072303,and 51821091)the Natural Science Foundation of Shaanxi Province(No.2019JQ-634)+1 种基金the 111 Project(No.B08040)the Fundamental Research Funds for the Central Universities.
文摘In this work,bulk Zr_(3)Al_(3)C_(5)-based ceramics were synthesized by the infiltration of A1-Si melt into zirconium carbide (ZrC) perform.The phase composition,microstructure,and mechanical properties of as-fabricated ceramics were studied.The results demonstrate that Si is more effective to reduce the twin boundary energy of ZrC than A1,and thus promotes the decrease of formation temperature of Zr_(3)Al_(3)C_(5).With the infiltration temperatures increasing from 1200 to 1500 ℃,the Zr_(3)Al_(3)C_(5) content increases from 10 to 49 vol%,which is contributed to the increase of flexural strength from 62±9 to 222±10 MPa,and fracture toughness (KIC) from 2.8+0.2 to 4.1±0.3 MPa.m^(1/2).The decrease of mechanical properties for the samples fabricated at 1600 ℃ is ascribed to the abnormal growth of Zr_(3)Al_(3)C_(5) grains.
