In this work, the CuAlBe shape memory alloy (SMA) with a new composition of 77.05Cu-22.02Al-0.93Be (at.%) detected by the EDS test was fabricated in a vacuum arc melter under a pure argon atmosphere. At the beginning, the high-purity (%99.9) elements of Cu, Al, and Be powders were mixed and the mixture (~ 10 g) was formed as pellets by pressure. By melting the pellets in arc melter, the as-cast ingot alloy was obtained. Then, the ingot alloy was cut into small pieces (~ 30–50 mg) and then all of these samples were all homogenized in the β-phase region (at 900 °C for 1 h) and immediately submerged in traditional iced-brine water to form β1’ martensite phase in the alloy which results from such fast cooling by suppressing the formation of hypoeutectoid precipitations (α and γ2). Then, to uncover and evaluate the existence of martensite structure and the characteristics of shape memory alloy properties of the alloy, the specimens were tested by calorimetric and structural measurements. The results of thermal heating/cooling cycles of the alloy were obtained from differential scanning calorimetry (DSC) measurements that were taken twice at 5 °C/min of heating/cooling rate under constant argon gas flow (100 ml/min) and by using liquid nitrogen cooling support to reach lower temperatures than room temperature. The DSC thermograms of the alloy revealed the characteristic martensitic transformation peaks that occurred endothermic by heating and exothermic by cooling at moderate temperatures ranging between 19 and 66 °C, regarded as evidence for the presence of shape memory effect property in the alloy. Important thermodynamical parameters such as transformation temperatures, hysteresis gap, and entropy and enthalpy change amounts for these back and forward martensitic phase transition peaks were determined directly by using data of DSC peak analyses and by calculation. Differential thermal analysis (DTA) measurement that was taken from room temperature to 900 °C at a heating/cooling rate of 25 °C/min displayed a high-temperature behavior of the alloy as compatible with the common behavior of Cu-Al SMAs. The X-ray test of the alloy conducted at room conditions showed sharp diffraction peaks and their matching crystal planes which indicate the existence of β1′ martensite phase in the alloy and its high single-like crystallinity i.e. its large Debye-Scherrer sub-micrometer crystallite size. Besides, theoretical forecasting about the existence and volumetric dominance of martensite phases was deduced from the calculated value of e/a (average conduction electron concentration per atom) parameter of the alloy. Furthermore, the mechanical Vickers microhardness tests that were performed at room temperature and under 100-gf load applied for 10 s revealed the high ductility and softness features of the alloy. Considering all the results, the highly ductile CuAlBe alloy with new composition owing shape memory alloy properties and intermediate working temperatures can be useful in various kinds of research and applications in which Cu-based SMAs are exploited.

中文翻译：

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CuAlBe形状记忆合金基本特性研究

在这项工作中，通过 EDS 测试检测到具有 77.05Cu-22.02Al-0.93Be (at.%) 的新成分的 CuAlBe 形状记忆合金 (SMA) 在纯氩气氛下的真空电弧熔炉中制造。开始时，将高纯度 (%99.9) 元素的 Cu、Al 和 Be 粉末混合，并通过压力将混合物 (~ 10 g) 形成为球团。通过在电弧熔化器中熔化球团，获得铸态合金锭。然后，将锭合金切成小块（约 30-50 毫克），然后所有这些样品都在 β 相区域均质化（在 900°C 下 1 小时），并立即浸入传统的冰盐水中通过抑制亚共析沉淀（α和γ2）的形成，在合金中形成β1'马氏体相，这是由于这种快速冷却造成的。然后，为了揭示和评估马氏体结构的存在和合金的形状记忆合金特性，通过量热和结构测量对试样进行了测试。合金的热加热/冷却循环的结果通过差示扫描量热法 (DSC) 测量获得，该测量在恒定氩气流量 (100 ml/min) 下以 5 °C/min 的加热/冷却速率进行两次，并使用液氮冷却支持达到低于室温的温度。合金的 DSC 热谱图显示了在 19 至 66°C 的中等温度下加热吸热和冷却放热的特征马氏体转变峰，这被视为合金中存在形状记忆效应特性的证据。这些前后马氏体相变峰的转变温度、滞后间隙、熵变和焓变等重要的热力学参数是利用DSC峰分析数据和计算直接确定的。以 25 °C/min 的加热/冷却速率从室温到 900 °C 进行差热分析 (DTA) 测量，结果显示合金的高温行为与 Cu-Al SMA 的常见行为兼容。合金在室温条件下进行的 X 射线测试显示出尖锐的衍射峰及其匹配的晶面，表明合金中存在 β1' 马氏体相及其高单晶度，即大的 Debye-Scherrer 亚微米微晶尺寸。除了，从合金的e/a（每个原子的平均传导电子浓度）参数的计算值推导出马氏体相的存在和体积优势的理论预测。此外，在室温下和在 100-gf 载荷下施加 10 秒的机械维氏显微硬度测试揭示了合金的高延展性和柔软性特征。考虑到所有结果，由于形状记忆合金特性和中间工作温度，具有新成分的高延展性 CuAlBe 合金可用于开发 Cu 基 SMA 的各种研究和应用。在室温和 100-gf 载荷下进行 10 秒的机械维氏显微硬度测试揭示了合金的高延展性和柔软性特征。考虑到所有结果，由于形状记忆合金特性和中间工作温度而具有新成分的高延展性 CuAlBe 合金可用于开发 Cu 基 SMA 的各种研究和应用。在室温和 100-gf 载荷下进行 10 秒的机械维氏显微硬度测试揭示了合金的高延展性和柔软性特征。考虑到所有结果，由于形状记忆合金特性和中间工作温度而具有新成分的高延展性 CuAlBe 合金可用于开发 Cu 基 SMA 的各种研究和应用。