Mo-12 Si-8.5 B alloys with different La2 O3 contents were fabricated by mechanical alloying and then hot pressing.The effects of La2 O3 on microstructure,room and elevated temperature mechanical properties of Mo-12 Si...Mo-12 Si-8.5 B alloys with different La2 O3 contents were fabricated by mechanical alloying and then hot pressing.The effects of La2 O3 on microstructure,room and elevated temperature mechanical properties of Mo-12 Si-8.5 B alloys were studied.The microstructure of Mo-12 Si-8.5 B alloy with La2 O3 additions exhibits a continuous α-Mo matrix,where the spherical Mo3 Si and Mo5 SiB2 intermetallic phases are distributed inside the grains and along the grain boundaries.The detailed microstructure shows that some nanoscale La2 O3 particles are dispersed mainly in the a-Mo grains and partially in the intermetallics.These La2 O3 particles can refine the grain sizes of a-Mo matrix and intermetallic,but the refining effect is limited with the La2 O3 addition further increasing.The mechanical testing results show that the La2 O3 addition simultaneously improves the compression strength and fracture toughness of Mo-12 Si-8.5 B alloy,due to that theα-Mo matrix is strengthened and toughened at ambient temperature and intermetallics are strengthened at elevated temperatures.The enhancing effect is sensitive to the amount of La2 O3 additions,and the Mo-12 Si-8.5 B alloy can obtain a better combination of strength and toughness when the content of La2 O3 is 0.9 wt%.展开更多
Three Laves phase-based alloys with nominal compositions of Cr2Nb-xTi （x = 20, 30, 40, in at%） have been prepared through vacuum non-consumable arc melting. The results show that the microstructures of Cr2Nb-（20, 3...Three Laves phase-based alloys with nominal compositions of Cr2Nb-xTi （x = 20, 30, 40, in at%） have been prepared through vacuum non-consumable arc melting. The results show that the microstructures of Cr2Nb-（20, 30） Ti alloys are composed of the primary Laves phase C15-Cr2（Nb,Ti） and bcc solid solution phase, while the microstructure of Cr2Nb-40Ti alloy is developed with the eutectic phases C15-Cr2（Nb,Ti）/bcc solid solution. The measured fracture toughness of ternary Laves phase C15-Cr2（Nb,Ti） is about 3.0 MPa m1/2, much larger than 1.4 MPa m1/2 for binary Laves phase Cr2Nb. Meanwhile, the fracture toughness of Cr2Nb-xTi （x = 20, 30, 40） alloys increases with increasing Ti content and reaches 10.6 MPa m1/2 in Cr2Nb-40Ti alloy. The eutectic microstructure and addition of Ti in Cr2Nb are found to be effective in toughening Laves phase-based alloys.展开更多
基金financially supported by the China Postdoctoral Science Foundation (No. 2016M602885)the National Natural Science Foundation of China (Nos.51371141 and 51701162)
文摘Mo-12 Si-8.5 B alloys with different La2 O3 contents were fabricated by mechanical alloying and then hot pressing.The effects of La2 O3 on microstructure,room and elevated temperature mechanical properties of Mo-12 Si-8.5 B alloys were studied.The microstructure of Mo-12 Si-8.5 B alloy with La2 O3 additions exhibits a continuous α-Mo matrix,where the spherical Mo3 Si and Mo5 SiB2 intermetallic phases are distributed inside the grains and along the grain boundaries.The detailed microstructure shows that some nanoscale La2 O3 particles are dispersed mainly in the a-Mo grains and partially in the intermetallics.These La2 O3 particles can refine the grain sizes of a-Mo matrix and intermetallic,but the refining effect is limited with the La2 O3 addition further increasing.The mechanical testing results show that the La2 O3 addition simultaneously improves the compression strength and fracture toughness of Mo-12 Si-8.5 B alloy,due to that theα-Mo matrix is strengthened and toughened at ambient temperature and intermetallics are strengthened at elevated temperatures.The enhancing effect is sensitive to the amount of La2 O3 additions,and the Mo-12 Si-8.5 B alloy can obtain a better combination of strength and toughness when the content of La2 O3 is 0.9 wt%.
基金financially supported by the National Natural Science Foundation of China (Nos.51074127 and 51104120)the SRF for ROCS,SEM
文摘Three Laves phase-based alloys with nominal compositions of Cr2Nb-xTi （x = 20, 30, 40, in at%） have been prepared through vacuum non-consumable arc melting. The results show that the microstructures of Cr2Nb-（20, 30） Ti alloys are composed of the primary Laves phase C15-Cr2（Nb,Ti） and bcc solid solution phase, while the microstructure of Cr2Nb-40Ti alloy is developed with the eutectic phases C15-Cr2（Nb,Ti）/bcc solid solution. The measured fracture toughness of ternary Laves phase C15-Cr2（Nb,Ti） is about 3.0 MPa m1/2, much larger than 1.4 MPa m1/2 for binary Laves phase Cr2Nb. Meanwhile, the fracture toughness of Cr2Nb-xTi （x = 20, 30, 40） alloys increases with increasing Ti content and reaches 10.6 MPa m1/2 in Cr2Nb-40Ti alloy. The eutectic microstructure and addition of Ti in Cr2Nb are found to be effective in toughening Laves phase-based alloys.
