DD6单晶合金蠕变特性及断裂机理

Creep Properties and Fracture Mechanism of DD6

在500MPa、900℃和300MPa、1000℃两种环境条件下,通过实验研究了[001]、[011]、[111]三种取向的镍基单晶合金DD6的蠕变特性及断裂机理。结果表明:DD6单晶高温合金蠕变性能具有明显的晶体取向相关性,在相同的温度和应力条件下,三种取向的单晶合金寿命差别很大,温度是影响[001]取向单晶合金蠕变寿命的主要因素,而应力则是影响[011]和[111]取向单晶合金蠕变寿命的主要原因。同时,晶体取向和实验条件的不同,都会使最小蠕变率发生变化,随着温度的升高,不同取向晶体的各向异性减弱,相同条件下,[111]取向最大蠕变量最大,[001]取向次之,[011]取向最小。而晶体取向对断裂机理有直接的影响,[001]、[111]取向DD6单晶合金的断裂是由微孔引起的断裂,[011]取向的DD6单晶合金在900℃、500MPa条件下的蠕变断裂为滑移断裂,1000℃、300MPa条件下的断裂为滑移面断裂和韧窝断裂二者兼有的混合型断裂。

Creep properties of Ni-base single crystals with , and orientations were studied under two loading conditions 500MPa,900℃ and 300MPa,1000℃.The results show that the creep properties of DD6 single crystals are strongly orientation dependent.Under the same temperature and stress conditions,fracture life is obviously different among the three orientations.Temperature is the major influence factor for the creep life of the crystals with orientation,while stress is the main reason for the creep life of the crystals with and orientations.The minimum creep rate is related with both of the loading condition and the crystal orientation.Anisotropy will reduce in all the crystals at higher temperature.Creep deformation decreases in the order of , and orientation.The rupture mode of the specimens with and orientations is microporous.For the orientational specimen,at 500MPa and 900℃,the fracture is induced by the slipping.At 300MPa and 1000℃,the fracture mode is the combination of slipping and dimples.