Abstract:The structure and properties of the new (Al,Cu)₄Ca, Al₂₇Ca₃Cu₇, and Al₈CaCu₄ intermetallic compounds in equilibrium with aluminum solid solution in the ternary Al-Ca-Cu alloying system were comprehensively analyzed. The (Al,Cu)₄Ca intermetallic compound is treated as a line phase based on the Al₄Ca phase with Cu substituted by Al. The solubility of copper in the compound reaches 10 at.% (19 wt.%), which leads to marked changes in the crystal lattice structure, physical and mechanical properties of the compound. For instance, the density of the compound increases from 2.22 to 2.79 g/cm³ and the microhardness from HV 180 to HV 250. The Al₂₇Ca₃Cu₇ phase is treated as a strict stoichiometric ternary compound with a primitive BaHg₁₁ type crystal structure of the Pm3m space group. The lattice parameter is accepted to be 8.514 ？ corresponding to a density of 3.45 g/cm³. The Al₈CaCu₄ phase is also a strict stoichiometric ternary compound with a tetragonal crystal lattice structure of the Mn₁₂Th type. The phase has the highest microhardness (HV 505) and density (4.57 g/cm³). The alloys pertaining to the binary (Al)+(Al,Cu)₄Ca phase field and the quasi-binary (Al)+Al₂₇Ca₃Cu₇ section can be considered promising as the base for new natural aluminum matrix composites.

Key words: intermetallics; Al-Ca alloys; microstructure; crystal structure; physical properties; mechanical properties