從TiN鋁化、Ti3Al氮化及TiN/Ti3Al界面反應探討AlN/Ti界面生成機構

Abstract

AlN/α-Ti的界面反應在經過1000℃/3 h熱處理，其生成相依序為δ-TiN/τ1-Ti3AlN/(τ1-Ti3AlN + α2-Ti3Al)兩相區/α2-Ti3Al。由AlN/α-Ti標記實驗可知原始界面位於AlN/δ-TiN。反應機制為AlN分解為Al與N往α-Ti往擴散，先生成δ-TiN與α2-Ti3Al，隨著反應時間增加，後續生成物皆在δ-TiN與α2-Ti3Al界面處發生。為了進一步了解Al、N與Ti原子在AlN/α-Ti界面的擴散情況，設計δ-TiN/α2-Ti3Al界面反應與α2-Ti3Al氮化、δ-TiN鋁化實驗。δ-TiN/α2-Ti3Al界面反應中經過1000℃/36 h的熱處理，生成相依序為τ2-Ti2AlN與τ1-Ti3AlN。經過1000℃/72 h熱處理，發現（α-Ti + δ-TiN）兩相區在δ-TiN與α2-Ti3Al的界面生成，兩相的方位關係為 與 。α2-Ti3Al經過1000℃氮化反應下，初期反應生成δ-TiN/τ1-Ti3AlN。在1000℃/3 h，生成相依序為δ-TiN/τ2-Ti2AlN/τ1-Ti3AlN。在1000℃/36 h，生成相依序為δ-TiN/τ2-Ti2AlN/γ-TiAl。在1000℃/72 h的δ-TiN鋁化反應生成相依序為TiAl3/AlN/τ2-Ti2AlN/δ-TiN。在AlN/Ti界面反應為N、Al原子供應較少的反應，在δ-TiN側受到鋁化生成τ1-Ti3AlN，在α2-Ti3Al側受到氮化生成δ-TiN、τ1-Ti3AlN。在α2-Ti3Al的氮化反應中，N原子供應充足，τ1-Ti3AlN受到氮化而形成τ2-Ti2AlN。在δ-TiN鋁化反應中，Al原子供應充足，τ1-Ti3AlN受到鋁化而生成τ2-Ti2AlN。藉由α2-Ti3Al氮化反應與δ-TiN鋁化反應可以證明當氮化與鋁化程度增加時，反應生成相為τ2-Ti2AlN。

The formation phases were δ-TiN/τ1-Ti3AlN/two-phase region （τ1-Ti3AlN + α2-Ti3Al）/α2-Ti3Al in sequence between AlN andα-Ti after annealing at 1000℃/3 h. The original interface of AlN/α-Ti diffusion couples examined by marked experiment at 1000℃/72 h, and the original interface was located between AlN and δ-TiN. The formation mechanism was that the Al and N atom decomposed of AlN diffused to α-Ti. δ-TiN and α2-Ti3Al formed at first, and then the other phases develop from the interface. The nitrided α2-Ti3Al, aluminizedδ-TiN and δ-TiN/α2-Ti3Al interfacial reaction were investigated in order to understand the Al, N and Ti atom diffusion. The τ2-Ti2AlN formed at the δ-TiN side and τ1-Ti3AlN formed at the α2-Ti3Al side between δ-TiN and α2-Ti3Al diffusion couples after annealing at 1000℃/36h. A two-phase （α-Ti + δ-TiN） was observed after annealing at 1000℃/72h with the relationship of and . For α2-Ti3Al nitriding at 1000℃,.δ-TiN and τ1-Ti3AlN were identified in the beginning. As the time increased, τ1-Ti3AlN was transformed to τ2-Ti2AlN and then the Al-rich phase γ-TiAl was formed. The formation phases of nitrided α2-Ti3Al at 1000℃/3 h were δ-TiN/τ2-Ti2AlN/τ1-Ti3AlN in sequence. The formation phases of nitrided α2-Ti3Al at 1000℃/36 h were δ-TiN/τ2-Ti2AlN/γ-TiAl in sequence. The aluminized layer in an aluminization of δ-TiN was formed about 20-60 μm after annealing at 1000℃ for 0.5 ~ 72h. The TiAl3, AlN and τ2-Ti2AlNwas found in aluminized layer after annealing at 1000℃/72h. An intergranular τ2-Ti2AlN was present in the δ-TiN with the orientation relationship and . By the result of nitrided α2-Ti3Al and aluminized δ-TiN, we knew that the formation depended on how the N and Al atom participated in the reaction. We found only τ1-Ti3AlN formed at AlN/Ti interfical reaction. If there were more N atoms, the τ1-Ti3AlN was transformed to τ2-Ti2AlN could be expected, such as the situation in nitrided α2-Ti3Al. In aluminized δ-TiN, the τ1-Ti3AlN was also aluminized to τ2-Ti2AlN.