Effect Of Ru And Ir On Microstructures And Creep Properties Of New-generation Nickel Base Single Crystal Superalloy

The effects of adding Ir and adding Ru and Ir on the solidification characteristics and microstructure of the nickel base single crystal superalloy include the following aspects.The addition of elements such as Ir and Ru affect the dendrite segregation of the elements.The addition of Ir reduce the dendrite segregation of alloy elements such as W,Mo and Ta,but slightly aggravates the dendrite segregation of Re and AL.The dendrite segregation of alloy elements is obviously reduced by Ru and Ir,particularly,Re,W both TCP phase formation is reduced dendritic segregation of elements doubled.Because of the segregation promotion of Al,which is the composition of ?'phase,The ?/?' eutectic in 0Ru3ir alloy increased from 9.2%of 0Ru0ir alloy to 12%,The 3Ru3Ir alloy relative to ORu0Ir alloy,eutectic area fraction decreased to 7.2%,The co-addition of Ru and Ir significantly inhibited the formation of?/?' eutectic structure.The ?' length of dendrites in the as-cast alloy is between 320 nm and 400nm,significantly smaller than the interdendritic position.In 0Ru3Ir and 3Ru3Ir alloys,the length of ?' phase in the interdendritic decreased from 500 nm to 460 nm and 400 nm,respectively.This is because the addition of Ru and Ir affects the dendritic segregation behavior of alloying elements,resulting in the finer precipitation ofy'phase between the dendrites 0Ru3Ir,3Ru3Ir alloy relative to ORuOIr alloy solution window temperature increased by 3?,temperature of solidus-liquiduslineof 3Ru3Ir alloy is increased 10? relative to the other two alloys.After 1330?/16 h solution treatment,and 1100?/4 h and 870?/24 h two-stage aging treatment of complete heat treatment,?' phase in the 0Ru3Ir alloys increases the size of about 20 nm than that of 0Ru0Ir alloy,but the number was not significantly increased.However,the addition of Ru and Ir significantly inhibited the size of ?'phase after complete heat treatment,which was reduced about 100 nm.but had little effect on the volume fraction of ?'phase.Long-term aging of the complete heat treatment alloy at 1100? showed that the TCP phase precipitation behavior of 0Ru3Ir alloy was the most obvious,which is mainly reflected by the maximum TCP area fraction of 0.9%and the longest average length over 40.m after 1100?/1000 h aging.The addition of Ir promoted the growth of TCP phase,but had no significant effect on the nucleation of TCP phase.The addition of Ru suppressed the nucleation of TCP phase.After TCP nucleation,it grows in a needle shape and then coarsens with the aging time and fusions.The creep test of the completely heat-treated alloy at 1150?/137 MPa found that the creep life of 0Ru0Ir alloy is over 100 h,the creep life of 0Ru3Ir alloy is 9 h,and the creep life of 3Ru3Ir alloy is 44 h.The TCP phase precipitates after 3Ru3Ir alloy creep deformation.