利用共焦激光扫描显微镜原位观察AISI 304不锈钢加热过程中高温δ相的形核与生长. 结果表明, 1300—1400℃之间δ相在γ晶界处优先析出, 而δ相在γ晶粒内“爆炸”形成需在1410℃以上; δ相形成主要受控于Ni原子的扩散; 提高升温速率有利于δ晶粒细化, 促使δ/γ平界面失稳并出现二次枝晶. δ相析出时以非小平面为主,另可见少量的小平面δ晶体; 随着相变进行, 小平面状δ相呈现出边缘钝化、向非小平面转变的趋势. 利用平直界面稳定临界扰动理论探讨了δ相生长界面失稳的机制, 并从结晶动力学对相生长方式转变的原因进行了分析.
The nucleation and growth behaviors of high-temperature δ during austenite (γ) → ferrite (δ) + liquid (L) phase transformation in an AISI30 stainless steel have been observed in-situ by using a confocal laser scanning microscope. The results show that δ appears prior from the γ crystal boundary at the temperature range from 1300 to 1400 0C, and appears at full blast in the γ gains above 1410 0C. The γ→δ+L phase transformation is controlled mainly the diffusion of Ni atoms near the γ/δ/L phase interface. With the increment of temperature risen rate, the size of δ gain decreases, the δ/γ planer interface becomes unstable, and a certain secondary branch appears. The δ grows mainly in the non-faceted style at first. Twin-crystal is the key shape of the sidestep forming in the δ/γ interface. The faceted δ trends to passivate its edge and transfers to non-faceted style with the γ →δ+L phase transformation. The mechanisms of the growth interface instability for δ are discussed by using the critical wavelength to stabilize a planar interface theory. The transformation reason for growth style of δ is analyzed by using the crystal dynamics theory.
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| [3] | |
| [4] | |
| [5] |
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