氧化釔/氧化鈣/氧化鋁複合材料與液態鈦合金(Ti-6Al-4V)之介面反應

Abstract

Y2O3/CaO/Al2O3依照不同莫耳比混合後，經過1500℃/30min熱壓成陶瓷複合材料試片，並與鈦合金(Ti-6Al-4V)在1atm氬(Ar)氣氛下，進行1700℃/30min之高溫擴散反應，探討在此製程參數下，陶瓷材料與鈦合金高溫擴散反應介面之影響。本實驗用X光繞射儀(x-ray diffraction, XRD)、掃描式電子顯微鏡(SEM/EDS)，分析擴散後的介面反應微觀結構。 研究結果發現Y2O3/CaO的試片與Ti-6Al-4V經高溫擴散反應後，僅微量的氧固溶至鈦中，於介面處形成一層Y2O3-X(Ca)的反應層，對於保護金屬側的效果良好。而隨著Al2O3添加量的增加，於擴散反應後，金屬側由Widmanstätten結構逐漸減少至消失，β'-Ti的量增多，最終轉變為Ti3Al。由於Ti與Al的親和力大於Y與Al的親和力，使得釔鋁化合物和鈣釔鋁化合物易於和Ti發生反應，於介面處形成Y2O3-x(Ca)。因為陶瓷內部的Al濃度較高，使得經由擴散進入的Ti固溶大量的Al，而生成Ti3Al或是Ti3Al+TiAl層狀結構。

Various composites of Y2O3, CaO and Al2O3 were hot pressed at 1500°C /30 MPa for 30 min and then reacted with titanium alloy (Ti-6Al -4V) at 1700°C/30 min. The microstructure of the reaction interface was characterized and analyzed using x-ray diffraction (XRD) and scanning electron microscopy (SEM/EDS). The results indicate that after the specimen(Y2O3/CaO) has high temperture diffusion reactions with Ti-6Al-4V, just few O solute in Ti-6Al-4V. It forms Y2O3-x(Ca) which has a good effect on protecting the metal surface at the interface. The strutures of Widmanstätten in metel surface gradually decreased and almost disappeared with increasing in the amounts of Al2O3.Eventually, the amounts of β'-Ti increase,and turns to Ti3Al. Because that the value of electron affinity between Ti and Al is greater than the one bewteen Y and Al.YAM, YAP, CaYAlO4 and CaYAl3O7 react readily to form Y2O3-x(Ca) at the interface.Besides,It form Ti3Al or lamellar structure(Ti3Al+TiAl) since Ceramics has higher concentration of Al,which led Al acting as the solute in a matrix of Ti.