EB-PVD制备的Ni-Cr-Al-Y高温合金箔力学性能

Mechanical properties of Ni-Cr-Al-Y superalloy foil by EB-PVD

采用一种新型的制备工艺———电子束物理气相沉积(EB PVD),制备厚度为0.2mm的Ni Cr Al Y高温合金箔材,并采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)等测试手段研究了Ni Cr Al Y高温合金的微观组织。结果表明,制备态的样品中存在柱状晶,这是由于制备过程中晶粒长大方式所导致的。经过760℃,16h真空热处理后,柱状晶转变为等轴晶,并析出γ′相。拉伸断口的SEM形貌表明,由于柱状晶之间组织疏松,结合较差,制备态样品沿柱状晶晶界发生脆性断裂,而热处理态样品的断口为典型的韧性断口。力学性能的测试结果表明,经过适当的热处理后,Ni Cr Al Y高温合金的室温和高温力学性能同制备态时相比,有明显的改善。在700℃时,热处理态样品抗拉强度为587.6MPa,应变为11.3%。

Ni-Cr-Al-Y superalloy foil with 0.2 mm thickness was fabricated by EB-PVD process, and its microstructure and mechanical properties were studied by SEM and TEM as well as mechanical analysis. The results show that there are column crystals in the as-deposited samples, which contribute to growing pattern of grains during the process of superalloy, and column crystals transform into equiaxed crystals after vacuum heat treatment at 760 ℃ for 16 h, and γ′phase is observed. Factograghs of tensile specimens show that brittle rupture occur along the intergranular of column crystals of as-deposited specimens, which attribute to the loose structures with weak cohesion between column crystals, and the fractures of annealed specimens are tough fractures. Test results of mechanical properties show that mechanical properties at round and high temperature are improved sharply, compared with those as-deposited specimens. The tensile strength of annealed specimens is 587.6 MPa,and the fracture strain is 11.3%.