鈦-鈮-鋯-錫系統合金之相變態與機械性能之研究

Study on Phase Transformation and Mechanical Properties of Ti-Nb-Zr-Sn Alloys

黃思穎(Sih-Ying Huang)

指導教授 ： 顏鴻威

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202002941

摘要

在本研究中探討了兩種新設計出之鈦-鈮-鋯-錫系統合金之顯微結構及機械性質，其合金成分分別為 Ti-16Nb-16Zr-6Sn及Ti-13Nb-16Zr-9Sn（重量百分比）。
麻田散型鈦合金Ti-16Nb-16Zr-6Sn在熱壓及固溶處理後具有約70 GPa的楊氏係數並且由α″相組成。此材料在特定溫度持溫時會發生脆化的現象是由恆溫ω相及Sn3Zr5所造成。另外晶粒細化作為一種穩定β相的方法可達到約47 GPa的楊氏係數及適當的延伸率其拉伸曲線展現出雙重降伏的現象。本實驗也顯示了在冷壓過程中所產生的α″織構會導致楊氏係數降低在本材料中40%的冷壓變形量可達到42 GPa的楊氏係數。
另一種合金Ti-13Nb-16Zr-9Sn擁有比室溫低的Ms溫度，並且在固溶處理後具有與Ti-16Nb-16Zr-6Sn不同的相組成。此實驗也討論了在Ti-16Nb-16Zr-6Sn中增加Sn與減少Nb對於機械性質與顯微結構的影響。
本研究宗旨為討論熱機處理對此兩種合金之機械性質及相變態之影響，並且進一步利用適當的熱機處理達到低楊氏係數的條件，開發出適合應用於生醫植入物之材料 。

關鍵字

鈦合金 ； 低楊氏係數 ； 晶粒細化 ； 織構 ； ω相 ； 脆化

並列摘要

In this research, evolutions of microstructure and mechanical properties in two newly designed Ti-Nb-Zr-Sn alloys were investigated, Ti-16Nb-16Zr-6Sn and Ti-13Nb-16Zr-9Sn (wt.%), respectively.
Martensitic titanium alloy Ti-16Nb-16Zr-6Sn possesses Young’s modulus about 70 GPa after hot-rolling followed by solution treatment, composed of α″ phase. Also, embrittlement was observed during aging at specific temperatures, caused by isothermal ω phase and Sn3Zr5 phase. What’s more, grain refinement was utilized as a strategy to stabilize β phase, leading to modulus of 47 GPa and proper elongation; the tensile curve undergoes double yielding phenomenon. It was revealed that α″ texture induced during cold-rolling process results in decreasing modulus. In this material, Young’s modulus as low as 42 GPa was accomplished by cold reduction of 40% without annealing.
The other alloy Ti-13Nb-16Zr-9Sn possesses martensitic transformation temperature (Ms temperature) lower than room temperature, exhibiting different phase constitutions from Ti-16Nb-16Zr-6Sn after solution treatment. Ti-13Nb-16Zr-9Sn was investigated to clarify effects of Sn addition and Nb reduction on microstructures and mechanical behaviors in the Ti-13Nb-16Zr-9Sn alloy.
The current work aims to discuss how thermomechanical treatment affects mechanical properties and phase transformation of these two Ti-Nb-Zr-Sn alloys. Moreover, we can further achieve low modulus conditions by proper thermomechanical treatment and develop materials having potential in biomedical implants application.

並列關鍵字

titanium alloys ； low modulus ； grain refinement ； texture ； ω phase ； embrittlement

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