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通过对一种定向凝固合金进行不同温度的固溶处理、蠕变性能测试及组织形貌观察,研究了固溶温度对枝晶臂/间区域的成分偏析及持久性能的影响。结果表明:经1230℃固溶及时效处理后,合金在枝晶干/间区域存在明显的成分偏析和组织不均匀性,粗大γ’相存在于枝晶间区域,细小γ’相存在于枝晶干区域,碳化物呈条状分布在枝晶间区域。合金经1260℃固溶及时效处理后,可明显降低合金中元素的偏析程度,并消除了合金在枝晶间区域存在中的粗大γ’相,使高体积分数细小立方γ’相均匀分布在枝晶间和枝晶干区域,并有细小粒状碳化物沿晶界析出,抑制晶界滑移,因此,可大幅度改善合金的中温蠕变性能。合金在中温蠕变期间的变形特征是位错在基体中滑移和剪切γ’相,并在γ’/γ两相界面形成位错网。蠕变后期,由于沿与应力轴呈45!角的晶界承受载荷的最大剪切应力,故裂纹易于在与应力轴呈45!角的倾斜晶界处萌生与扩展。
The effects of solution temperature on the composition segregation and permanent properties of dendrite arm / intergranular zone were studied by solid solution treatment, creep test and microstructure observation of a directional solidified alloy at different temperatures. The results show that there are obvious segregation and microstructure irregularities in the dendrites dry / intergranular zone after solid solution treatment and aging treatment at 1230 ℃. The coarse γ ’phase exists in the interdendritic region and the fine γ’ phase exists in the branch Crystalline dry region, carbide strip distribution in the interdendritic region. After solution treatment and aging treatment at 1260 ℃, the segregation of the elements in the alloy can be obviously reduced and the coarse γ ’phase in the interdendritic region of the alloy can be eliminated, so that the fine cubic γ’ phase with high volume fraction is uniformly distributed in Dendrites and dendrite dry area, and a small granular carbide precipitation along grain boundaries, grain boundary slip inhibition, therefore, can significantly improve the alloy creep properties at medium temperature. The deformation characteristics of the alloy during creep at medium temperature are dislocations that slip and shear the γ ’phase in the matrix and form a dislocation network at the γ’ / γ two-phase interface. In late creep, the crack tends to initiate and expand at oblique 45 ° angle grain boundaries with the stress axis due to the maximum shear stress at the 45 ° angle along the stress axis.