Investigation on the tensile properties of PtAl and PtReAl coated Ni₃Al-based single crystal superalloy

Tensile tests of uncoated, diffusion Pt-aluminide (PtAl) coated and Re modified PtAl (PtReAl) coated Ni₃Al-based single crystal superalloy were conducted at room temperature (RT) and 1100 °C to investigate the effect of coating on the tensile behaviors and the cracking mechanism. The results revealed that the PtAl and PtReAl coatings had significantly impaired the ultimate tensile strength of the superalloy by about 10% at room temperature, ascribed to the decreasing true bearing section of the coated specimens caused by the cracking of the brittle coatings. At 1100 °C, the PtAl and PtReAl coating improved the oxidation resistance and ductility of the superalloy. However, due to the low high-temperature strength of the coatings, the yield strength and the ultimate tensile strength of the PtAl coated superalloy showed a reduction of about 19% and 17% when compared to the uncoated superalloy. Moreover, the PtReAl coated specimen presented relatively lower strength than PtAl coated specimen, which is attributed to the internal oxidation of the Re-rich layer during the tensile test process at 1100 °C.