新型Ni-Co基高温合金中平衡析出相的热力学研究

来源期刊：金属学报2010年第3期

论文作者：王衣 孙锋 董显平 张澜庭 单爱党

文章页码：334 - 339

关键词：Ni-Co基高温合金； 热力学计算； 析出相； 错配度

Key words：Ni-Co base superalloy； thermodynamic calculation； precipitation phase； mismatch

摘    要：利用热力学计算软件JMatPro和相应的镍基高温合金数据库,研究了U720Li合金以及在此基础上研发的新型Ni-Co基高温合金的化学成分对平衡相的析出行为、加工性能和γ/γ′晶格错配度的影响.结果表明:Ti/Al值(原子比)的增加提高了合金中γ/γ′相的晶格错配度,γ′析出相的含量随Ti+Al含量(原子分数)的增加而增加.因此,增加Ti/Al值和Ti+Al含量能提高合金的高温强度.Co含量的升高可以拓宽合金的加工窗口,改善合金的加工能力,并且还可以增加合金γ/γ′相的晶格错配度,提高合金错配强化的效果.同时,Ti/Al值的增加促进合金中η相析出,而Co含量的增加具有抑制η相的效果.因此,在Co含量较高的Ni-Co基高温合金中,适当提高Ti含量,增加Ti/Al值对提高合金高温强度有利.

Abstract: Thermodynamic properties of the traditional U720Li alloy and the new Ni-Co base superalloy have been studied using JMatPro and the latest relevant database for Ni base superalloys. The effects of chemical composition on the equilibrium precipitation phases,process-ability and γ/γ’ mismatch have been analyzed.It is found that the γ/γ’ mismatch increases with the increase of Ti/Al (atomic ratio).The volume fraction of γ’ is proportional to the Ti+Al contents(atomic fraction). Therefore,by increasing the Ti/Al ratio and Ti+Al content,the yield strength of alloys can be improved. On the other hand,the γ’ solvus temperature decreases by Co additions.As a result,the range of processing temperature is extended.The γ/γ’ mismatch also increases with Co additions,which adds additional strengthening to the alloy.Moreover,high Ti/Al ratio or low Co content promotes the precipitation ofηphase.Thus,Ni-Co base superalloys with high Ti+Al content,Ti/Al ratio and Co content bear an improved strength,phase stabilities and process-ability.