氧化鋯與鈦金屬高溫擴散反應之介面分析

Abstract

本實驗利用TEM/EDS、SEM/EDS、XRD來鑑定ZrO2與Ti經 1550℃/0.5hr擴散反應後之介面微觀結構。在氧化鋯側，氧化鋯易 還原成缺氧氧化鋯(ZrO2-x)，而靠近界面處氧化鋯晶粒較小，氧化 鋯晶粒大小由介面處向陶瓷側遞增，原因是固溶鈦可以抑制氧化鋯晶 粒成長。氧化鋯擴散進入鈦側的量遠大於鈦擴散進入氧化鋯側的量， 以致氧化鋯側接近界面處變成多孔性的組織。在鈦側，鈦金屬在高溫 時可固溶大量的Zr及O元素，以α-Ti(Zr, O) 與/或 β-Ti(Zr, O)相存 在，溫度冷卻至常溫時，在鈦側有殘留的β-Ti(Zr, O)，以及α-Ti(Zr, O) 與Ti2ZrO兩相交錯存在的層狀組織。殘存β-Ti(Zr, O)存在的原因在 於固溶大量的Zr元素，抑止β→α相變化。而α-Ti(Zr, O)與Ti2ZrO 兩相交錯的層狀組織中，α-Ti(Zr, O)為hexagonal結構，而Ti2ZrO為 orthorhombic 結構；α-Ti(Zr, O)與Ti2ZrO之間方位關係為 [00．1]α-Ti //[001]Ti2ZrO及(10．0)α-Ti //(1 0 )Ti2ZrO。

Hot pressed 3 mol%Y2O3-ZrO2 was reacted with titanium at 1550℃/0.5 hr. The interface was characterized by TEM/EDS, SEM/EDS, XRD, and microhardness. In the ceramic side, zirconia was easily reduced to oxygen-deficient zirconia (ZrO2-X). Pores were found near interface in the ceramic side, because the diffusion of oxygen and zirconium into titanium was much faster than the diffusion of Ti into zirconia. The grain growth of zirconia at the interface was suppressed by the dissolution of titanium. The grain size of zirconia was small near the interface and increased gradually away from the interface. The residual β-Ti(Zr, O) and the lamellae structure of α-Ti(Zr, O) and Ti2ZrO formed in the titanium side during cooling down to the room temperature. The residual β-Ti(Zr, O) existed due to the dissolution of large amount of Zr which restrained β→α phase transformation. α-Ti(Zr, O) and Ti2ZrO were identified to be hexagonal and orthorhombic, respectively, with the orientation relationship of [00．1]α-Ti //[001]Ti2ZrO and (10．0)α-Ti //(1 0 )Ti2ZrO。