The aluminum corner of the previously unexplored quaternary eutectic Al-Cu-Ca-Si system promising for the design of new heat treatable alloys have been studied using thermodynamic modeling and experimental techniques. The experimental data have revealed the presence in equilibrium of a previously undescribed quaternary compound identified as a strict stoichiometric AlCaSiCu phase with a tetragonal I4/mmm structure (Pearson symbol: tI10) and the lattice parameters = 4.04 Å and = 11.00 Å. The phase has a density of 3.36 g/cm and a microhardness of 335 Hv. In accordance with the suggested structure of the phase diagram, its region that can be promising for the design of heat treatable alloys contains three (Al)+AlCu+AlCaSiCu, (Al)+AlSiCa+AlCaSiCu and (Al)+AlCu+AlSiCa quasi-ternary sections and two (Al)+AlCu+AlSiCa+AlCaSiCu and (Al)+AlCu+AlCaSiCu+Si four-phase fields. Analysis of the precipitation hardening response for the new quaternary Al-5 wt%Cu-Ca-Si alloys suggests that it is not inferior (the obtained peak hardness is ∼125 Hv) to that for the alloys Al-5 wt% Cu (∼120 Hv) and Al-4 wt%Si-5 wt%Cu (∼125 Hv) based on the conventionally used systems. However, to obtain noticeable hardening at aging, the content of silicon should be at least 1.1–1.2 times higher than that of calcium. A comparative hot tearing susceptibility (HTS) study revealed that the new heat treatable Al-5 wt%Cu-Ca-Si alloys have higher hot tearing resistances (HTS ∼16 mm according to a pencil probe) than that of the Al-5 wt%Cu base alloy (HTS >16 mm).

中文翻译：

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用于设计沉淀硬化合金的新型四元共晶 Al-Cu-Ca-Si 体系

使用热力学建模和实验技术对先前未开发的四元共晶 Al-Cu-Ca-Si 系的铝角进行了研究，该系有望用于设计新型可热处理合金。实验数据揭示了平衡状态下存在一种先前未描述的四元化合物，该化合物被确定为严格化学计量的 AlCaSiCu 相，具有四方 I4/mmm 结构（皮尔逊符号：tI10），晶格参数 = 4.04 Å 和 = 11.00 Å。该相的密度为 3.36 g/cm3，显微硬度为 335 Hv。根据相图的建议结构，其可用于热处理合金设计的区域包含三种(Al)+AlCu+AlCaSiCu、(Al)+AlSiCa+AlCaSiCu和(Al)+AlCu+AlSiCa准-三元截面和两个(Al)+AlCu+AlSiCa+AlCaSiCu和(Al)+AlCu+AlCaSiCu+Si四相场。对新型四元 Al-5 wt%Cu-Ca-Si 合金的沉淀硬化响应的分析表明，它并不逊于合金 Al-5 wt% Cu（～ 120 Hv) 和 Al-4 wt%Si-5 wt%Cu (∼125 Hv) 基于常规使用的系统。然而，为了在老化时获得明显的硬化，硅的含量应至少比钙的含量高1.1-1.2倍。热撕裂敏感性 (HTS) 比较研究表明，新型可热处理 Al-5 wt%Cu-Ca-Si 合金比 Al-5 wt% 合金具有更高的抗热撕裂强度（根据铅笔探针，HTS ∼16 mm） %Cu 基合金（HTS >16 mm）。