| Title |
Control of Microstructure and Mechanical Properties by Heat Treatment of a Mechanically Alloyed ODS Ni - Base Superalloy |
| Authors |
류호진(Ho Jin Ryu); 홍순형(Soon Hyung Hong); 김영길(Young Gil Kim) |
| Abstract |
The effects of heat treatment on the γ′precipitation and the mechanical properties of a newly developed mechanically alloyed(MA) oxide dispersion strengthened(ODS) Ni-base superalloy were investigated. When the solution treatment temperature of ODS Ni-base superalloy was above 1260℃, the γ′precipitates were completely dissolved and uniform sizes of γ′precipitates were formed during the cooling from the solution treatment temperature. While, when the solution treatment temperature of ODS Ni-base superalloy was below 1260℃, bimodal sizes of γ′consisted of coarse and fine γ′ precipitates were observed after cooling from the solution treatment temperature. During the aging treatment at 954℃, the average size of γ′precipitates increased with increasing the aging time. The ODS Ni-base superalloy with γ′precipitates less than 0.25㎛ was deformed dominantly by shearing the precipitates by pairwise dislocation. While the ODS Ni-base superalloy with γ′precipitates larger than 0.28㎛ was deformed dominantly by the Orowan bypass mechanism. An equation to estimate the yield strength of ODS Ni-base superalloy with bimodal sizes of γ′ precipitates, based on the rule of-mixture was proposed. |