材料期刊网

本文研究了铸造镍基高温合金中沉淀的片状μ相,揭示了μ相的形成规律、化学成份、TTT曲线、断裂特征和对力学性能的影响。研究结果表明,μ相的形成温度范围很宽,从800—1140℃。片状μ相的宽面是六方指数的{0001},它沿基体γ的{111}面板出。在760℃以下冲击,拉伸和持久的断裂特征是沿μ相{0001},面解理断裂,电子空位数N_v值不是控制μ相形成的唯一因素,还与(Mo+W)at.-％和Mo(Mo+W)有关。此外,硼也是抑制μ相的有效因素。

Studies were made of the formation and chemical composition of precipitated plate like μ-phase as well as its effect on the TTT curve, fracture feature and mechanical properties of cast nickel base superalloy. It was found that the temperature of formation of plate like μ-phase is within wide range from 800 to 1140℃. Its baseplane is parallel to the hexagonal plane {0001}. It precipitates from plane {111} of γ-matrix. The cleavage fracture feature under impact, tensile and stress tests below 760℃ appears along baseplane {0001} of μ-phasc. For the superalloy containing 1—1.5 wt-％ μ-phase, the impact value at 20℃, the stress rupture life and the tensile ductility at 20℃ and 760℃ decrease obviously, but the stress rupture ductility increases distinctly, especially under elevated temperatures. The (?)_v value seems to be not the only factor to control the μ-phase formed, and yet to relate to both (Mo+W) at.-％ and Mo/(Mo+W). Besides, the boron content may also be effective to retard its formation.