固溶温度对FGH95镍基合金持久断裂机制的影响

通过对不同温度固溶处理的FGH95合金进行组织形貌观察及持久性能测试,研究了组织结构对合金持久性能及其断裂机制的影响。结果表明:经1150℃固溶和时效处理后,合金中有粗大γ′相在较宽的边界区域不连续分布,其周围存在γ′相贫化区;经1160℃固溶及时效处理后,合金中粗大γ′相完全溶解,在晶内弥散分布高体积分数的γ′相,并有粒状(Nb,Ti)C碳化物在晶内及沿晶界不连续析出;经1165℃固溶和时效后,合金的晶粒尺寸明显长大,并有硬而脆的碳化物膜沿晶界连续析出。在650℃/1034MPa条件下,经1160℃固溶和时效的合金,由于在晶界处不连续析出的粒状碳化物对晶界具有钉扎作用,可有效阻碍晶界滑移,使合金具有较好的抗蠕变性能。合金蠕变后期的变形特征是晶内发生单取向和双取向滑移,随着蠕变进行,滑移迹线增多,并在晶界处引起应力集中,致使裂纹在晶界处萌生及扩展并最终导致断裂。

Effects of Solution Temperatures on Enduring Fracture Mechanism of FGH95 Nickel-Base Superalloy

By means of the enduring properties measurement and microstructure observation,the influence of the microstructure on the enduring properties and fracture mechanism for FGH95 nickel-base superalloy was investigated.The results show that after solution treated at 1150 ℃,the thicker phase is distributed discontinuously in the wider boundary regions in which exists the poor-zone of the finer phase.When the solution temperature rises to 1160 ℃,the thicker phase in the alloy is fully dissolved,and the fine phase with high volume fraction is dispersively distributed within the grains,and thereinto the particles of(Nb,Ti)C carbide phase are discontinuously precipitated along the boundaries.After solution treated at 1165 ℃,the grain sizes are obviously grown up,and the films of the carbide is continuously precipitated along the boundary.The particle carbides which are discontinuously precipitated along the boundary can effectively pin the grain boundaries and restrain boundaries sliding,resulting in the alloy possessing better enduring properties under the applied stress of 1034 MPa at 650 ℃.In the later stage of creep,the deformed characteristic of the alloy is single and double orientation slipping,and the slipping trace on the sample surface increases to bring out the stress concentration as the creep goes on,which results in the initiating and propagating of the micro-cracks along the boundaries up to rupture.