Diffusion Layer Growth and Compound Formation Sequence of Titanium-Carbon Steel Tri-metal Composite (Ti-Ni-steel) Sheets Fabricated by Hot-roll Diffusion Bonding

熱軋擴散製程結合鈦－鎳－碳鋼金屬複合（Ti-Ni-steel）薄板探討擴散層形成及生成順序

林俊銘(Chun-Ming Lin)

《中國機械工程學刊》 42卷6期 (2021/12) Pp. 587-594

摘要

The primary objective in this work was to investigate the diffusion layer growth and compound formation sequence of titanium-carbon steel tri-metal composite sheets fabricated. Those results give a useful insight into the effects of different processing temperatures on the interface evolution at the Ti/Ni interface in hot-roll diffusion-bonded Ti/Ni/ steel joints, and observations of microstructure and thermodynamic calculations revealed some interesting results. During the diffusion process, Ni_3Ti and NiTi2 begin nucleation at nearly the same time; therefore, the thickness of the two layers was very similar. Finally, Ti and Ni diffuse to the interface between the NiTi_2 and Ni_3Ti compound layers to form NiTi. As the thickness of the NiTi layer increases, part of Ni3Ti is consumed; leading to a reduction in its thickness, it can be attributed to the lower reaction Gibbs free energies and surface energy increments of Ni_3Ti and NiTi_2. The α + β Ti phases additionally exist as discrete needle-shaped particles in the matrix of Ni_3Ti phase, while β- Ti phases exist as discrete islands in the matrix of NiTi_2 phase. The presence of Ni in the interfacial zone adjacent to the Ti substrate stabilizes β-Ti phase, leads to the formation of needle-shaped α + β-Ti phase.

關鍵字

Diffusion layer growth ； Compound formation ； Tri-metal composite sheets ； Hot-rolling ； Diffusion bonding

並列摘要

本文旨在探討熱軋擴散製程對鈦－碳－鋼（Ti-Ni-steel）三金屬複合板的擴散層形成及生成順序。其結果，深入了解不同加工溫度對熱軋擴散結合的Ti/Ni/steel接合Ti/Ni界面演變的影響，以及對微觀結構觀察和熱力學計算揭示了一些有趣的結果。在擴散過程中，Ni_3Ti和NiTi_2幾乎同時開始形核；因此，兩層的厚度非常相似。最後，Ti和Ni擴散到NiTi_2和Ni_3Ti化合物層之間的界面，形成NiTi。隨著NiTi層厚度的增加，部分Ni_3Ti被消耗掉；導致其厚度減小，這可歸因於較低的反應吉布斯自由能和Ni_3Ti和NiTi_2的表面能增量。α + β Ti相在Ni3Ti相的基體中另外以離散的針狀顆粒形式存在，而β-Ti相在NiTi_2相的基體中以離散的島狀存在。與Ti基體相鄰的界面區中Ni的存在穩定了β-Ti相，導致形成針狀α+β-Ti相。