使用激光增材制造技术制备TC4/TC11钛合金梯度材料典型沉积试样,测量沉积过程中3个特征位置的温度历程,并对沉积试样进行显微组织观察.建立了激光增材制造TC4/TC11梯度材料结构温度场预测有限元模型.有限元模型的温度场计算结果与试验结果吻合较好,同时有限元模型所计算的Tβ温度转变线位置与试样显微组织中观察得到的结果一致.显微组织观察结果表明,试样中无缺陷,顶部为等轴晶区域,从增材底部到等轴晶区域之间存在贯穿整个增材区域的柱状晶;在Tβ温度转变线两侧微观组织有明显不同:最后一层增材过程中,温度超过Tβ的组织冷却后为超细α+β网篮组织,温度未达到Tβ的组织冷却后为带有大量α集束的α+β网篮组织;在设计界面(材料组分变化位置)处组织连续、无突变.%A typical specimen of TC4/TC11 titanium alloy gradient material was deposited by laser additive manu-facturing technology. The temperature history of the three characteristic positions during the deposition process was mea-sured and the microstructure of the deposited sample was observed. A finite element model for temperature field predic-tion of laser additive manufacturing TC4/TC11 gradient material structure was established. The results of the temperature field calculation of the finite element model are in good agreement with the experimental results. And the Tβtemperature transition line position calculated by the finite element model is in good agreement with the observation results in the microstructure of the sample. The microstructure observation shows that there is no defect in the sample. The top area is equiaxed grain region, and there is a columnar crystal region through the whole material increasing area from the bottom to the equiaxed crystal region. The microstructure on both sides of the Tβtemperature transition line is significantly different:during the process of finishing the last layer, the area where temperature exceeds Tβproduces ultrafine α+β basket wave mi-crostructure, and will produce α+β basket wave microstructure with a mass of α clusters if the temperature is below Tβ. The microstructure is continuous and no mutation at the design interface (material composition change position).
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