Microstructure and fatigue properties of TiAlbased alloys with different W contents were investigated.The results indicate that the grain size and lamellar spacing can be significantly refined,and the optimal W conten...Microstructure and fatigue properties of TiAlbased alloys with different W contents were investigated.The results indicate that the grain size and lamellar spacing can be significantly refined,and the optimal W content on both the microstructure and fatigue property is about1.00 at%.The amount of B2（ω） phase gradually increases with the increase in W content,and excessive B2（ω） phase located in the boundary of lamellar colony trends to be the weak region with low resistance against crack propagation.Another result is that with the increase in W content,the region of peritectic reaction is also enlarged.The interdendritic Al-rich region is another weak region against crack propagation.Both of these effects are responsible for the worse fatigue property of Ti-45.1Al-5Nb-1.40W-1.4B W alloy compared with that of Ti-45.7Al-5Nb-0.75W-1.4B alloy.Instability of fatigue property still exists,but it slightly reduces with the decrease in grain size and lamellar spacing.展开更多
Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-ric...Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-rich intermetallic phases, and in particular the porosity in comparison with primary A356. The average area percent and size(length) of Fe-rich intermetallics change from about 0.5% and 6 μm in A356 to 2% and 25 μm in 356 alloy. The average area percent and maximum size of porosity also increase from about 0.4% and 420 μm to 1.4% and 600 μm, respectively. As a result, tensile ductility decreases about 60% and ultimate tensile strength declines about 8%. Lower fatigue strength was also experienced in the secondary 356 alloy. Low cycle fatigue(LCF) strength decreased from 187 MPa in A356 to 159 MPa in 356 and high cycle fatigue(HCF) strength also declined slightly from 68 MPa to 64 MPa.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 50971106 and 50211141)the National Higher-Education Institution General Research and Development Fund (No. 2682014CX005)
文摘Microstructure and fatigue properties of TiAlbased alloys with different W contents were investigated.The results indicate that the grain size and lamellar spacing can be significantly refined,and the optimal W content on both the microstructure and fatigue property is about1.00 at%.The amount of B2（ω） phase gradually increases with the increase in W content,and excessive B2（ω） phase located in the boundary of lamellar colony trends to be the weak region with low resistance against crack propagation.Another result is that with the increase in W content,the region of peritectic reaction is also enlarged.The interdendritic Al-rich region is another weak region against crack propagation.Both of these effects are responsible for the worse fatigue property of Ti-45.1Al-5Nb-1.40W-1.4B W alloy compared with that of Ti-45.7Al-5Nb-0.75W-1.4B alloy.Instability of fatigue property still exists,but it slightly reduces with the decrease in grain size and lamellar spacing.
文摘Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-rich intermetallic phases, and in particular the porosity in comparison with primary A356. The average area percent and size(length) of Fe-rich intermetallics change from about 0.5% and 6 μm in A356 to 2% and 25 μm in 356 alloy. The average area percent and maximum size of porosity also increase from about 0.4% and 420 μm to 1.4% and 600 μm, respectively. As a result, tensile ductility decreases about 60% and ultimate tensile strength declines about 8%. Lower fatigue strength was also experienced in the secondary 356 alloy. Low cycle fatigue(LCF) strength decreased from 187 MPa in A356 to 159 MPa in 356 and high cycle fatigue(HCF) strength also declined slightly from 68 MPa to 64 MPa.
