Allvac 718Plus alloy is a compromising Ni-based superalloy at elevated-temperature of 704℃,due to its combination of good mechanical properties and excellent structure stability.The precipitation behaviors during hea...Allvac 718Plus alloy is a compromising Ni-based superalloy at elevated-temperature of 704℃,due to its combination of good mechanical properties and excellent structure stability.The precipitation behaviors during heat treatment in Allvac 718Plus alloy processed by rapid solidification technique were systematically investigated in this work.The evolution of secondary phases in rapidly solidified(RS)718Plus alloy during annealing at 960℃is:η+MC in 1 h,η+MC+Laves(C14)in 6 h,and MC+Laves(C14)in longer duration.The growth and dissolution behaviors ofηphase are evidenced in RS samples and different types of dislocations at theη/γinterface are characterized.Based on these experimental observations,we examine the transformation mechanisms ofγ→ηandη→γ,which are related to the formation of stacking faults(SFs)with a1/6[211]γShockley partial dislocation and the climbing of14[0001]ηedge dislocations at theη/γinterface,respectively.Both MC and Laves(C14)phases are enriched in Nb and Mo,with a higher level of Ti in MC carbides and Cr in the Laves(C14)phase.The precipitation of MC carbides is driven by the high concentration of C atoms inγ-matrix,while the Cr segregation promotes the later nucleation of Laves(C14)phase inγ-matrix around MC carbides,which is due to the Cr atoms rejection from MC carbides into the matrix.展开更多
基金National Natural Science Foundation of China(Nos.52034004 and 52122409)for grant and financial support。
文摘Allvac 718Plus alloy is a compromising Ni-based superalloy at elevated-temperature of 704℃,due to its combination of good mechanical properties and excellent structure stability.The precipitation behaviors during heat treatment in Allvac 718Plus alloy processed by rapid solidification technique were systematically investigated in this work.The evolution of secondary phases in rapidly solidified(RS)718Plus alloy during annealing at 960℃is:η+MC in 1 h,η+MC+Laves(C14)in 6 h,and MC+Laves(C14)in longer duration.The growth and dissolution behaviors ofηphase are evidenced in RS samples and different types of dislocations at theη/γinterface are characterized.Based on these experimental observations,we examine the transformation mechanisms ofγ→ηandη→γ,which are related to the formation of stacking faults(SFs)with a1/6[211]γShockley partial dislocation and the climbing of14[0001]ηedge dislocations at theη/γinterface,respectively.Both MC and Laves(C14)phases are enriched in Nb and Mo,with a higher level of Ti in MC carbides and Cr in the Laves(C14)phase.The precipitation of MC carbides is driven by the high concentration of C atoms inγ-matrix,while the Cr segregation promotes the later nucleation of Laves(C14)phase inγ-matrix around MC carbides,which is due to the Cr atoms rejection from MC carbides into the matrix.
