J. Mater. Sci. Technol. ›› 1989, Vol. 5 ›› Issue (2): 90-95.
ZHENG Yunrong;WANG Luobao;LI Chenggong Institute of Aeronautical Naterials, Beijing, China. To whom correspondence should be addressed.
ZHENG Yunrong;WANG Luobao;LI Chenggong Institute of Aeronautical Naterials, Beijing, China. To whom correspondence should be addressed.
摘要: <正> Hf lowers the incipient melting temperatureof superalloy. As carbon content in Hf-bearingalloy decreases, the incipient melting temperaturedrops furthey. PD ingots have stronger tendencyto incipient melting than HRS ones. Even thoughin PD ingot, the sensitivities at both endsof the ingot are quite different. The meltingof Ni_5Hf phase may be considered as one of themain factors affecting incipient melting. Themore Ni_5Hf the alloy contains, the more seriousthe incipient melting becomes. The results ofdifferential thermal analysis (DTA) have provedthat the peak of 1135-1160℃corresponds tothe melting range or Ni_5Hf. By means of apretreatment at 1150℃, 8h, Ni_5Hf phase can beeliminated in two ways: the reactionNi_5Hf+γ(C)→MC_(2)+γand solid solution, andtherefore the final solid solution treatmentcan be carried out at 1260℃. This brings abouta high homogenized structure and further increasesthe stress rupture properties of the alloy at1040℃, 140 MPa.