Al0.88Cu0.94Fe0.18

The intermetallic phase with composition Al0.88Cu0.94Fe0.18 was synthesized by high-temperature sintering of a mixture with initial chemical composition Al78Cu48Fe13. Al0.88Cu0.94Fe0.18 adopts the CsCl structure type in space-group Pm m.

however, such a given structure model only represents a possibility inferred from the composition rather than a refined one.
In the present study, the crystal structure model for the �-phase in the Al-Cu-Fe system has been refined on basis of single-crystal X-ray diffraction data.This phase has similar lattice parameters to the previously reported �-phase.Its chemical composition was refined to be Al 0.88 Cu 0.94 Fe 0.18 , in accordance with the complementary EDX results (see Table S1 of the supporting information).

Synthesis and crystallization
The high-purity elements Al (indicated purity 99.95%; 0.7163 g), Cu (indicated purity 99.99%; 1.0372 g) and Fe (indicated purity 99.9%; 0.2485 g) were mixed in the molar ratio 78:48:13 and ground in an agate mortar.The blended powders were placed into a cemented carbide grinding mound of 9.6 mm diameter and pressed at 4 MPa for about 3 min.The obtained cylindrical block was put into a silica glass tube and vacuum-sealed by a home-made sealing machine.The resulting ampoule then was placed in a furnace (SG-XQL1200) and heated up to 1373 K for 2 h with with a heating rate of 10 K min À 1 .The temperature was then reduced to 1073 K for 10 h.temperature by turning off the furnace power.Suitable pieces of single-crystal grains were broken and selected from the product for single-crystal X-ray diffraction.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1.All atoms in the unit cell cooccupied the Wykoff positions.Different choices of refinement are listed in Table S2 of the supporting information.The maximum and minimum residual electron densities in the final difference map are located 0.0 A ˚and 1.01 A ˚from the atoms Cu1.

Table 1
Experimental details.