(1. 上海大學(xué) 省部共建高品質(zhì)特殊鋼冶金與制備國(guó)家重點(diǎn)實(shí)驗(yàn)室，上海 200444； 2. 上海大學(xué) 材料科學(xué)與工程學(xué)院，上海 200444； 3. 中國(guó)科學(xué)院 金屬研究所，沈陽(yáng) 110016； 4. 上海大學(xué) 材料基因組工程研究院，上海 200444)
摘 要: 通過(guò)相場(chǎng)法研究了1073K時(shí)效過(guò)程中Ni-Al高溫合金γ′相的析出動(dòng)力學(xué)。結(jié)果表明：在形核長(zhǎng)大階段，隨Al成分增加，γ′相的生長(zhǎng)動(dòng)力學(xué)指數(shù)m值總體呈下降趨勢(shì)，當(dāng)ρ≈0.5(ρ為γ′相半徑與平均半徑的比值)時(shí)，γ′相數(shù)目達(dá)到最大，小于該尺寸的γ′相幾乎不存在。在γ′相的粗化階段，γ′相的生長(zhǎng)動(dòng)力學(xué)指數(shù)m值介于2~3之間，γ′相的生長(zhǎng)機(jī)制為溶質(zhì)擴(kuò)散與界面遷移共同作用的混合機(jī)制。粗化階段γ′相的尺寸分布符合Gamma分布，且粗化后期滿足標(biāo)度律。在γ′相的粗化后期，隨時(shí)間的延長(zhǎng)，γ′相的尺寸均勻性越好，且隨Al成分增加，γ′相的粗化機(jī)制有從溶質(zhì)擴(kuò)散機(jī)制向界面遷移機(jī)制的過(guò)渡。
關(guān)鍵字: 鎳基高溫合金；相場(chǎng)法；析出動(dòng)力學(xué)；生長(zhǎng)機(jī)制；動(dòng)力學(xué)指數(shù)
（1. State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200444, China; 2. School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China; 3. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China; 4. Institute of Material Genome, Shanghai University, Shanghai 200444, China）
Abstract:The kinetics of the γ′ phase precipitation for Ni-Al superalloys at 1073K was studied by the coherent phase-field method. The results shows that, at the nucleation and growth stages, as the Al composition increases, the kinetic exponent m of γ′ phase growth shows an overall declining trend. It is difficult to determine the growth mechanism of the γ′ phase. According to the γ′ phase size distribution at the nucleation and growth stages, it is known that the number of γ′ phase particles reaches the maximum near ρ=0.5 (ρ is the ratio of γ′ phase radius to its average radius). The particles with size smaller than ρ=0.5 are much less. During the coarsening stage, the range of m value is between 2 and 3. The growth mechanism of the γ′ phase is hybrid comprised of the solute diffusion mechanism and the boundary migration mechanism. The size distribution of γ′ phase at the coarsening stage approaches the Gamma distribution and satisfies the scaling rule at the late period of coarsening. Besides, as the Al composition increases, γ′ phase size becomes more uniform and γ′ phase coarsening mechanism changes from the solute diffusion mechanism to boundary migration mechanism.
Key words: Ni-based superalloy; phase-field method; precipitation kinetics; growth mechanism; kinetic exponent
