Ti–Ta thin films exhibit properties that are of interest for applications as microactuators and as biomedical implants. A Ti–Ta thin film materials library was deposited at T = 25 °C by magnetron sputtering employing the combinatorial approach, which led to a compositional range of Ti₈₇Ta₁₃ to Ti₁₄Ta₈₆. Subsequent high-throughput characterization methods permitted a quick and comprehensive study of the crystallographic, microstructural, and morphological properties, which strongly depend on the chemical composition. SEM investigation revealed a columnar morphology having pyramidal, sharp tips with coarser columns in the Ti-rich and finer columns in the Ta-rich region. By grazing incidence X-ray diffraction four phases were identified, from Ta-lean to Ta-rich: ω phase, α″ martensite, β phase, and a tetragonal Ta-rich phase (Ta_(tetr)). The crystal structure and microstructure were analyzed by Rietveld refinement and clear trends could be determined as a function of Ta-content. The lattice correspondences between β as the parent phase and α″ and ω as derivative phases were expressed in matrix form. The β ⇌ α″ phase transition shows a discontinuity at the composition where the martensitic transformation temperatures fall below room temperature (between 34 and 38 at. % Ta) rendering it first order and confirming its martensitic nature. A short study of the α″ martensite employing the Landau theory is included for a mathematical quantification of the spontaneous lattice strain at room temperature (ϵ̂_max = 22.4(6) % for pure Ti). Martensitic properties of Ti–Ta are beneficial for the development of high-temperature actuators with actuation response at transformation temperatures higher than 100 °C.

中文翻译：

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组合磁控溅射制备Ti-Ta薄膜材料库的晶体结构分析

Ti-Ta薄膜展现出的特性对于作为微致动器和生物医学植入物很有用。利用组合方法通过磁控溅射在T = 25°C的条件下沉积了Ti-Ta薄膜材料库，从而形成了Ti ₈₇ Ta ₁₃至Ti ₁₄ Ta ₈₆的成分范围。随后的高通量表征方法可以对晶体学，微观结构和形态学特性进行快速而全面的研究，而这在很大程度上取决于化学成分。SEM研究显示出具有金字塔状尖锐尖端的柱状形态，富钛的柱较粗，富钽的柱较细。通过掠入射X射线衍射，确定了从贫Ta到富Ta的四个相：ω相，α''马氏体，β相和一个四方富Ta相（Ta _（tetr））。通过Rietveld精炼分析了晶体结构和微结构，可以确定明显的趋势作为Ta含量的函数。以母体形式表示β为母相，以α''和ω作为导数相的晶格对应关系。β⇌α''相变在马氏体相变温度降至室温以下（介于Ta的34％至38 at。％之间）以下的成分时显示为不连续，使其成为一阶并确认其马氏体性质。包括使用Landau理论对α''马氏体进行的简短研究，以对室温下的自发晶格应变进行数学量化（ϵ̂ _max对于纯Ti = 22.4（6）％。Ti-Ta的马氏体性质有利于高温致动器的开发，该致动器在相变温度高于100°C时具有致动响应。