Ti-47Al-2Cr-2Nb合金熔体与Y_2O_3型壳的界面作用

Interfacial Reaction between Ti-47Al-2Cr-2Nb Alloy Melt and Y_2O_3 Shell Mold

结合定向凝固工艺要求,研究了不同加热温度和保温时间(1600℃×10min,1600℃×30min和1700℃×10min、1700℃×30min)下,Ti-47Al-2Cr-2Nb合金熔体与Y2O3型壳的界面作用、界面组织形貌、元素分布以及界面生成物的相组成,并讨论了Y2O3型壳用于TiAl基合金铸件定向凝固的可行性。结果表明,相同的保温温度或保温时间下,熔体中的Al元素比Ti元素更易向型壳一侧扩散;同时合金棒表层形成一层几十微米厚的渗透层,1600℃试样表面渗透层是由于合金液对型壳面层材料的浸蚀和热冲击作用,使Y2O3颗粒进入到基体中形成的;而1700℃试样渗透层中在Y2O3颗粒的周围发现含Y、O、Al的灰色相,应为Y2O3与合金液发生反应而形成。

Interfacial reaction,interfacial microstructure,element distribution and phase constituent of Ti-47Al-2Cr-2Nb alloy melt with Y2O3 shell mold were investigated in condition of different heating temperature and holding time combining with directional solidification technology.Feasibility of Y2O3 shell mold for directional solidification TiAl alloy parts was approached.The results show that,at a given holding temperature or holding time,Al element in the melt is more easily diffused into the mold shell side than Ti element.Meanwhile,infiltrated layer with 40～70μm in thickness can be formed on surface of the alloy rod.Formation of infiltrated layer at 1600 ℃ is attributed to the introduction of Y2O3 particle into the matrix alloy as a result of erosion and thermal impaction of liquid alloy to face materials of shell mold,while it is the result of reaction of Y2O3 with liquid alloy at 1700 ℃ because of the occurrence of grey phase containing Y,O,Al around Y2O3 particle.