Pt-Al涂层对DD413合金高温拉伸性能的影响

Influence of Pt-Al Coating on Tensile Properties of DD413 Alloy at High Temperatures

利用SEM和TEM对比研究了无涂层和Pt-Al涂层试样在760和980℃的拉伸性能。研究结果表明:在2个温度下,Pt-Al涂层试样的屈服强度均低于无涂层试样。由于Pt-Al涂层存在韧脆转变温度(ductile to brittle transition temperature,DBTT),因此在不同温度下涂层表现出不同的变形机制和裂纹萌生方式。在高温下由于β向γ′转变有利于位错产生滑移,从而导致Pt-Al涂层的塑性变形。Pt-Al涂层在DBTT以上拉伸强度的提高是由于Pt在β-NiAl相中起到固溶强化效应。

The Pt-Al coating is a vital section of aero-engine power blades that can improve the operating temperature of the blade.The blade is subjected to axial tensile stress during operation.Both the oxidation of the Pt-Al coating and the microstructure evolution caused by the element diffusion between the coating and the matrix at high temperatures affect the service performance of the blade.However,the specific mechanisms remain unclear.In this work the effect of Pt-Al coating on the tensile properties of a DD413 alloy was studied.SEM and TEM were used to compare the tensile properties of the uncoated and Pt-Al-coated samples,respectively,at 760 and 980oC.Lower yield strength was detected in Pt-Alcoated samples than that in uncoated samples at 760 and 980oC.The different crack initiation modes and deformation mechanisms of Pt-Al coating at 760 and 980oC mainly result from the ductile to brittle transition temperature(DBTT).At high temperatures,the transition fromβtoγ′is conducive to the dislocation slip,which leads to the plastic deformation of the Pt-Al coating.The increase in the tensile strength of the Pt-Al layer above DBTT can be attributed to the solidified solution-strengthening effect of Pt inβ-NiAl.