摘要
本文主要利用SEM，XRD，TEM與STEM-EDS儀器，分析鈦-8鋁-1釩-1鉬合金之顯微結構，合金β/(α+β)轉換溫度介於1020-1040℃，Ms轉換溫度介於880-900℃。合金退火組織結構，分析結果如下︰ 合金經1080℃退火，基本顯微結構為針狀α'+α2混合之麻田散體組織，於層狀α'/α'相界可觀察IP1相(HCP結構)形成，針狀麻田散體組織存在共同垂直平面(0001)。合金再經400℃或600℃處理，於層狀α'/α'邊界可觀察到β相與IP2(FCC結構)相形成。合金於Ms溫度以上之α+β雙相區域退火，其基本組織結構為α+α'雙相組織。於β/α+β溫度以下30℃左右，除初析α相區外，α'相區域觀察結果與1080℃試片一致。略高於Ms溫度以上(900℃)退火，則存在顆粒狀β相析出物於α相基地形成，且α/β相邊界可觀察到IP2相；合金再經400℃/32h處理，則可觀察到ω相於β相中析出。另外，本文觀察到一種新的高鉬、高碳、高磷之析出相(W相)，具BCT結構，其晶格常數為a=0.940nm，b=c=1.012nm。合金於Ms溫度以下之α+β雙相區域退火，其基本組織結構為α+β雙相組織，另可觀察到板條狀β相於α相區域分解析出，且可觀察IP2界面相。STEM-EDS成份分析結果顯示︰鉬元素的聚集量，而矽元素的擴散對界面相(β相、IP1相與IP2相)的形成，扮演相當的重要角色。
並列摘要
The temperatures of the β/α+β and Ms phase transition of the Ti-8Al-1V-1Mo alloy are in the range of 1020-1040℃ and 880-900℃, respectively. The purposes of the present studies are to investigate the annealed structures of the alloy by using of SEM, XRD, TEM and STEM-EDS equipments. The main results are described as following: The microstructure of the alloy annealed at 1080℃ is essentially an (α'+α2) mixture lamellar-martensite structure. Some inter-phase IP1 belonging to HCP structure are formed on the α'/α' boundaries. During heated at 400℃ or 600℃, some β-phase and IP2-phase precipitates belonging to FCC structure are observed on α'/α' boundaries. Being annealed at 1000℃ below α/(α+β) transition about 30℃, the phase transitions in the α' region are similar to that observed of the 1080℃ specimens. And, annealed at 900℃ above Ms transition, some β-phase particles formed within the α-phase matrix and some IP2- phase precipitates are also observed on the α/β boundaries. In addition, during heated at 400℃, some ω-phase particles precipitate within the β matrix. In the meanwhile, being annealed at 900℃, a new W-phase precipitates with higher Mo and C elements are found. The lattice parameters of the W-phase can be identified to a=0.940 nm, b=c= 1.012nm. Annealed at 800℃below Ms transition, the microstructure of the alloy is essentially an (α+β) mixture bimodal structure. Some plate-like β-phase particles formed within α matrix and on the α/α boundaries. Some IP2-phase precipitates are also observed on the α/β boundaries. Moreover, based on the examination of STEM-EDS, it is imply that the cluster of Mo element and the diffusion of Si element will play an important roles on the inter-phase precipitates such as β-phase, IP1-phase and IP2-phase.