【摘要】 利用光学显微镜、扫描电镜和透射电镜研究了Ti600高温钛合金在550℃长期时效至2000 h过程中的微观组织演化行为与机理。结果表明：Ti600合金在550℃长期时效下稀土相较为稳定，但α₂相和硅化物S₂相析出并逐渐长大。0～500 h的时效初期，随时效时间的增加，与基体共格的球状α₂相的尺寸和数量增加，但当时效至500 h后，α₂相的析出与长大趋于稳定，时效至2000 h, α₂相的尺寸仍保持在10 nm以内。硅化物S₂相在α片层与β相界面或α相内析出，且当时效时间超过200 h后其长大逐渐明显，并且沿着长轴方向生长使其形状逐渐向棒状转变。时效至2000 h,合金中S₂相的平均尺寸已经达到约175 nm。经计算，550℃长期时效S₂相的长大速率K=2.69×10³ nm³·h^-1。其中Zr的扩散主要控制S₂相的长大。更多还原

【Abstract】 Microstructure evolution behavior and mechanism of high temperature Ti600 titanium alloy during long-term aging at 550 ℃ for 0-2000 h were studied by means of optical microscope, scanning electron microscopy and transmission electron microscopy. The results show that the rare earth phase in the Ti600 alloy is maintained relatively stable during long-term aging at 550 ℃, but α₂ phase and silicide S₂ phase are promoted to precipitate and grow up. At the early stage of aging, the size and number of spherical α₂ phase coherent with the matrix increase as the aging time increases from 0 to 500 h. However, after aging for 500 h, the precipitation and growth of the α₂ phase tend to be stable. After aging for 2000 h, the size of the α₂ phase remains within 10 nm. The silicide S₂ phase is induced to precipitate at the interface between the lamella α and β phase or within the α phase, and its growth gradually becomes obviously after the aging time exceeds 200 h, and it grows along the long axis direction, gradually transforming its shape into a rod shape. After aging for 2000 h, the average size of the S₂ phase in the alloy has reached about 175 nm. After calculation, the growth rate of the S₂ phase during long-term aging at 550 ℃ is K=2.69×10³ nm³·h^-1. The diffusion of Zr mainly controls the growth of the S₂ phase.更多还原