(1. 中南大學 粉末冶金國家重點實驗室，長沙 410083；2. 株洲中航動力精密鑄造有限公司，株洲 412000)
摘 要: 針對當前雀斑判據在合金成分上存在的不足，構建一個基于高溫合金成分的雀斑預測模型并對其進行了驗證。通過對合金各元素的密度溶質膨脹系數β和密度溫度膨脹系數βT的計算，定量分析其在凝固過程中對糊狀區(qū)液相密度的影響。通過定義一個雀斑形成傾向因子P，量化各個元素對雀斑形成的影響大小。并在此基礎上，構建一個慮及合金成分的雀斑預測模型，該模型可以預測不同組分的合金和雀斑形成之間影響規(guī)律。3種不同來源的k值(如實驗值、二元合金相圖和Thermo-Calc計算的平衡分配系數)被代入該模型計算，驗證哪種k值能更好地預測雀斑形成。結果表明：基于二元合金相圖的k值，預測結果與實驗結果擬合較差，其線性擬合優(yōu)度R2最大時僅為0.4；而采用實驗和Thermo-Calc的k值，擬合較好，v2最大值分別達到0.87和0.95。最后，計算SX系列合金的P值，結果顯示：單位含量的Hf元素對雀斑有最強的抑制作用，Ta元素的抑制作用次之；Al、Re元素對雀斑有較強的促進作用，W元素的促進作用次之。
關鍵字: 雀斑；高溫合金；成分；雀斑形成傾向因子；平衡分配系數；預測模型
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Zhuzhou AVIC Power Investment Casting Co., Ltd., Zhuzhou 412000, China）
Abstract:Aiming at the currently shortage of the freckle criterion in the alloy constituents, a constituent-based freckle predictor for nickel-base suppalloy was modeled and verified by the experiment data. The effect of each element on the liquid density was quantitatively analyzed by calculating the solutal expansion coefficient β and the thermal expansion coefficient βT of each element. The impact of each element was quantified by defining a freckle formation tendency factor. Based on calculations of these variables, a constituent-based freckle predictor was modeled, which can predict the influence between different alloy constituents and freckle formation. Three different equilibrium distribution coefficients k were taken into this model and verified which was the best k value to predict freckle. The results show that the fitting of the number of freckles using the k value based on binary phase diagram is poor, and the linear goodness-of-fit (R2) maximum is only 0.4; while using the k values of experiment and Thermo-Calc the fitting is good, and the maximum R2 reach 0.87 and 0.95, respectively. Finally, the P values were calculated for the SX alloys, and the results show that the hafnium has the strongest influence on freckle prevention, tantalum also has beneficial effects though not as pronounced as hafnium; aluminum and rhenium have the stronger promoting effect on freckles, and tungsten is the second.
Key words: freckle; superalloy; constituent; freckle formation tendency factor; equilibrium distribution coefficient; prediction model
