This work reviews recent progress in the alloy design,microstructure,and mechanical properties of refractory high-entropy alloys(RHEAs).What’s more,the underlying strengthening mechanisms and deformation behavior are...This work reviews recent progress in the alloy design,microstructure,and mechanical properties of refractory high-entropy alloys(RHEAs).What’s more,the underlying strengthening mechanisms and deformation behavior are discussed.Composed mainly of near-equimolar refractory elements,RHEAs have superior mechanical properties,especially at high temperatures.However,many of them have limited room-temperature ductility.Much work has been done to solve this trade-off,and some of the RHEAs have the potential to be used for high-temperature applications in the future.In addition to their mechanical properties,RHEAs have other attractive properties,such as biocompatibility and wear resistance,which are discussed.Finally,current problems and future suggestions for RHEAs are discussed.展开更多
The effect of boron content on grain refinement of commercially pure aluminum by Al-5Ti-1B was quantitatively assessed.When the boron content is less than 0.03 wt.%,the refining performance of Al-5Ti-1B gradually is w...The effect of boron content on grain refinement of commercially pure aluminum by Al-5Ti-1B was quantitatively assessed.When the boron content is less than 0.03 wt.%,the refining performance of Al-5Ti-1B gradually is weakened as the boron content increases,which is attributed to the reaction of boron with the Al_(3)Ti interlayer on TiB_(2)and the consumption of solute Ti.On the contrary,when the boron content exceeds 0.03 wt.%,the refining performance of Al-5Ti-1B gradually recovers with increasing boron content,which is related to the formation of primary AlB_(2)particles that provide additional nucleant substrates.展开更多
The permeability of a new investment casting mold system prepared by adding needle cokes has been investigated in this work. The permeability tests of the molds were carried out at the temperature of 25—1 200?C.The r...The permeability of a new investment casting mold system prepared by adding needle cokes has been investigated in this work. The permeability tests of the molds were carried out at the temperature of 25—1 200?C.The results showed that the addition of needle cork could significally increase the permeability of the molds by a factor of about 4 because the burning of needle cokes increased the porosities of the molds. Meanwhile, the needle coke modified molds exhibited higher green strength and greater thickness both on flat section and at sharp edges compared with the full fused silica mold. Taking account of the mold thickness, the needle coke modified molds had increased adjusted fracture load(AFL) by a factor of about 2 at the test temperature of 25—1 200?C. The addition of needle coke significally improved the permeability of the molds during both autoclaving and casting,and optimized the correlation between the permeability and green strength of the molds.展开更多
基金the National Natural Science Foundation of China(Nos.51871147,51821001)the Shanghai Aerospace Advanced Technology Joint Research Fund,China(No.USCAST2020-35).
文摘This work reviews recent progress in the alloy design,microstructure,and mechanical properties of refractory high-entropy alloys(RHEAs).What’s more,the underlying strengthening mechanisms and deformation behavior are discussed.Composed mainly of near-equimolar refractory elements,RHEAs have superior mechanical properties,especially at high temperatures.However,many of them have limited room-temperature ductility.Much work has been done to solve this trade-off,and some of the RHEAs have the potential to be used for high-temperature applications in the future.In addition to their mechanical properties,RHEAs have other attractive properties,such as biocompatibility and wear resistance,which are discussed.Finally,current problems and future suggestions for RHEAs are discussed.
基金the financial supports from the National Natural Science Foundation of China(Nos.U1832183,52090042,51821001)。
文摘The effect of boron content on grain refinement of commercially pure aluminum by Al-5Ti-1B was quantitatively assessed.When the boron content is less than 0.03 wt.%,the refining performance of Al-5Ti-1B gradually is weakened as the boron content increases,which is attributed to the reaction of boron with the Al_(3)Ti interlayer on TiB_(2)and the consumption of solute Ti.On the contrary,when the boron content exceeds 0.03 wt.%,the refining performance of Al-5Ti-1B gradually recovers with increasing boron content,which is related to the formation of primary AlB_(2)particles that provide additional nucleant substrates.
基金the 13th Five-Year Common Technology Equipment Development Project(No.41423040206)the Industry-University-Research Cooperation Annual Plan of Shanghai(No.CXY2016004)
文摘The permeability of a new investment casting mold system prepared by adding needle cokes has been investigated in this work. The permeability tests of the molds were carried out at the temperature of 25—1 200?C.The results showed that the addition of needle cork could significally increase the permeability of the molds by a factor of about 4 because the burning of needle cokes increased the porosities of the molds. Meanwhile, the needle coke modified molds exhibited higher green strength and greater thickness both on flat section and at sharp edges compared with the full fused silica mold. Taking account of the mold thickness, the needle coke modified molds had increased adjusted fracture load(AFL) by a factor of about 2 at the test temperature of 25—1 200?C. The addition of needle coke significally improved the permeability of the molds during both autoclaving and casting,and optimized the correlation between the permeability and green strength of the molds.
