摘要
The effects of joining temperature(TJ)and time(tJ)on microstructure of the transient liquid phase(TLP)bonding of GTD-111 superalloy were investigated.The bonding process was applied using BNi-3 filler at temperatures of 1080,1120,and 1160℃ for isothermal solidification time of 195,135,and 90 min,respectively.Homogenization heat treatment was also applied to all of the joints.The results show that intermetallic and eutectic compounds such as Ni-rich borides,Ni−B−Si ternary compound and eutectic-γcontinuously are formed in the joint region during cooling.By increasing tJ,intermetallic phases are firstly reduced and eventually eliminated and isothermal solidification is completed as well.With the increase of the holding time at all of the three bonding temperatures,the thickness of the athermally solidified zone(ASZ)and the volume fraction of precipitates in the bonding area decrease and the width of the diffusion affected zone(DAZ)increases.Similar results are also obtained by increasing TJ from 1080 to 1160℃ at tJ=90 min.Furthermore,increasing the TJ from 1080 to 1160℃ leads to the faster elimination of intermetallic phases from the ASZ.However,these phases are again observed in the joint region at 1180℃.It is observed that by increasing the bonding temperature,the bonding width and the rate of dissolution of the base metal increase.Based on these results,increasing the homogenization time from 180 to 300 min leads to the elimination of boride precipitates in the DAZ and a high uniformity of the concentration of alloying elements in the joint region and the base metal.
研究连接温度和时间对瞬时液相连接GTD-111高温合金显微组织的影响。连接过程采用BNi-3填料,在1080、1120和1160℃下,分别进行195、135和90 min的等温凝固,再进行均匀化热处理。结果表明,在冷却过程中,接头区域连续形成富Ni硼化物、Ni−B−Si三元化合物和共晶γ的金属间化合物和共晶化合物。随着连接时间的延长,金属间化合物相首先减少,最终被消除,等温凝固完成。三种温度下,随着保温时间的增加,非热凝固区(ASZ)的厚度和结合区析出相的体积分数减小,扩散影响区(DAZ)的宽度增大。将连接温度从1080℃提高到1160℃,保温90 min,得到的结果相似。而且,当温度从1080℃提高到1160℃,ASZ的金属间化合物更快被消除。然而,继续升温至1180℃后在连接区又观察到金属间化合物相。随着温度的升高,连接区宽度和母材的溶解速率增大。另外,将均匀化时间从180 min增加到300 min,可消除DAZ中的硼化物析出相,且接头区域和母材中合金元素浓度具有较高的均匀性。
