基于CAFE模型的CMSX4鎳基合金定向凝固過程顯微組織模擬

基于CAFE模型的鎳基合金定向凝固過程顯微組織模擬Microstructure simulation during directional solidification of nickel-based alloy based on CAFE model

采用CAFE模型(Cellular automata finite element method)模擬第二代鎳基高溫合金CMSX4凝固過程中的晶粒生長，并探討澆注溫度和冷卻速度對凝固組織的影響。結果表明:凝固開始時，首先在鑄錠底部會形成一層取向隨機的細小等軸晶，由于晶粒間的競爭生長，晶粒數(shù)目減小，晶粒尺寸增大，á001？晶向與熱流方向偏離角較大的晶粒逐漸被偏離角較小的晶粒淘汰。澆注溫度的提高會使晶粒尺寸變大、晶粒數(shù)目變小，而冷卻速度的升高卻會使晶粒尺寸變小，與理論分析一致。

CAFE model was adopted to simulate the grain growth during solidification process of the second generation nickel-based superalloy CMSX4, and then the influences of casting temperature and cooling rate on the solidification structure were discussed. The results show that at the beginning of solidification, a layer of fine equiaxed grains with random orientation forms first. Due to the competition between the grain growth, the number of grains decreases, the grain size increases, and the grains with bigger deviation angle of the á001？ crystal orientation deviating from the direction of heat flow are gradually eliminated by the grains with small deviation angle. The increase of pouring temperature will make the grain size bigger, the number of crystal grains decreases, while the increase of cooling rate can make the grain size smaller. The results are consistent with the theoretical analysis.

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