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采用定向凝固炉制备出含有不同V含量的柱状晶合金,进行了高温蠕变性能测试和微观组织形貌观察,研究合金化元素V对镍基柱状晶合金微观组织及高温蠕变性能的影响。结果表明:低V含量的合金中碳化物主要以棒状形式存在,而高V合金中碳化物主要以块状形式存在,棒状碳化物中的V含量低于块状碳化物。随V含量的增加,合金中碳化物由棒状向块状转变,当V含量达到1.04%(质量分数)时,碳化物的形貌已经完全转变成块状。铸态合金经固溶处理后,合金中的碳化物发生溶解,低V合金中的棒状碳化物溶解较多,而高V合金中碳化物溶解较少。在980℃/216 MPa和760℃/725 MPa条件下低V柱状晶合金持久寿命较短,高V合金持久寿命较长,提高合金中的V含量有利于提高合金的蠕变寿命。高V合金与低V合金相比,时效和蠕变期间在晶界析出M_(23)C_6型碳化物数量少。蠕变期间合金中的裂纹主要在晶内MC型碳化物及晶界析出的M_(23)C_6型碳化物处萌生和扩展。
The columnar crystal alloys with different V content were prepared by directional solidification furnace. The creep property at high temperature and the microstructure were observed. The effect of alloying element V on the microstructure and creep property of Ni-based columnar crystal was studied. The results show that the carbides in the alloy with low V content mainly exist in the form of rods, whereas the carbides in the high V alloy mainly exist in the form of lumps, and the V content in the rod carbides is lower than that of the bulk carbides. With the increase of V content, the carbides in alloy changed from rod to block. When the content of V reached 1.04% (mass fraction), the morphology of carbides changed completely into lumps. After the as-cast alloy is solution treated, the carbides in the alloy dissolve, the rod-shaped carbides in the low-V alloy dissolve more, and the carbides in the high-V alloy dissolve less. Under the conditions of 980 ℃ / 216 MPa and 760 ℃ / 725 MPa, the low V columnar alloy has a shorter lasting life and the higher V alloy has a longer lasting life. Increasing the V content in the alloy helps to improve the creep life of the alloy. Compared with the low-V alloy, the high-V alloy precipitates less M_ (23) C_6 carbides at the grain boundaries during aging and creep. The cracks in the alloy during the creep mainly occurred in the intragranular MC-type carbides and M_ (23) C_6-type carbides precipitated at the grain boundaries.