新型钴基高温合金中W元素对蠕变组织和性能的影响

Effects of W Concentration on Creep Microstructure and Property of Novel Co-Based Superalloys

以γ’相强化的Co-Al-W高温合金(Co-9Al-xW,x=8、9、10,原子分数,%)为研究对象,耦合CALPHAD和晶体塑性本构关系,建立了高温加载时微观组织演化的三元弹塑性相场模型,考察了W含量对蠕变过程中γ’相演化行为和蠕变性能的影响。结果表明,随W含量增加,γ’相体积分数增加,γ基体塑性变形降低,筏化形成并提前,导致蠕变性能提高。不变矩分析表明,9W和10W合金中筏组织形成是出现稳态蠕变阶段的主要原因。应力/应变分析表明,高W合金γ基体中较大的错配应力减小了塑性变形。

γ' precipitate strengthened cobalt-based alloys exhibit superior comprehensive properties and are potential candidates for the anticipated next-generation superalloy.The phase field method,which considers the combined effect of multiple energy fields,effectively elucidates the processing and mechanism of microstructure evolution.By using the ternary elastoplastic phase field model coupled with CALPHAD and crystal plasticity model,the γ' evolution of Co-9Al-xW(x = 8,9,and 10;atomic fraction,%) alloys during creep processes is simulated herein.The corresponding rafting behaviors and creep properties are evaluated from the perspective of the changes in second-order moment invariant map(SOMIM) and stress/strain fields.The results show that as the W content increases,the volume fraction of the γ' phase increases,the plastic strain in the γ matrix reduces,and rafting occurs with accelerated rate,which enhances the creep property.Further,the SOMIM analysis shows that the raft structure leads to a steady creep behavior in 9W and 10W alloys.In addition,the alloy with a high W content has a high misfit stress in the γ matrix,which leads to a low plastic strain.