研究了不同热处理对一种含Re的新型镍基单晶高温合金组织和性能的影响. 结果表明, 通过差热分析法确定合金的固相线和液相线温度分别为1339和1371 ℃, 由金相测试法测出初熔温度介于1305~1310 ℃范围内. 初熔组织中主要表现为Ti的严重富集, 其次为B和S. 在1080, 1100和1120 ℃分别时效4 h后空冷, 获得的γ' 相均具有较高的正方度. 合金的最佳热处理制度为1290 ℃, 2 h+1320 ℃, 4 h, A.C.+1100 ℃, 4 h, A.C.+900 ℃, 24 h, A.C.. 采用该制度处理后的单晶高温合金中各元素偏析系数明显降低, 持久性能优异, 在1070 ℃, 140 MPa条件下的持久寿命达到78.2 h.

Nickel base single crystal superalloys are widely used to fabricate turbine blade materials, since they have high temperature capability, excellent mechanical and environmental properties. Re is known as a very efficient solid-solution element that increases high temperature strength, so novel single crystal superalloys contain a high level of Re content. Whereas enhancement of Re in the dendrite arms facilitates inhomogeneous distribution of other alloy elements, it become difficult and important to determine the heat treatment in Re-containing single crystal superalloys. Effects of heat treatments on microstructure and properties in a new Re-containing single crystal superalloy have been investigated in this work. The solidus and liquidus temperature measured by differential thermal analysis (DTA) is 1339 and 1371 ℃, respectively. The incipient melting temperature determined by metallographic testing method is in the range between 1305 and 1310 ℃. The results show that Ti resides preferentially followed by B and S in the incipient melting regions. γ' precipitates all display cubic after 4 h aged at 1080, 1100 and 1120 ℃ followed by air cooling (A.C.). The optimum heat treatment is 1290 ℃, 2 h+1320 ℃, 4 h, A.C.+1100 ℃, 4 h, A.C.+900 ℃, 24 h, A.C.. Microsegregation of alloy elements reduces significantly after this heat treatment. The rupture property performs well and the rupture life is up to 78.2 h under the condition of 1070 ℃ and 140 MPa.