In this work, closed-cell aluminum foams with 4 wt.% contents of short-cut basalt fibers (BFs) were successful prepared by using the modified melt-foaming method. The pore size of BF-containing aluminum foam and commercially pure aluminum foam was counted. The distribution of BF and its effect on the compressive properties of closed-cell aluminum foams were investigated. The results showed that the pore size of BF-containing aluminum foams was more uniform and smaller. BF mainly existed in three different forms: Some were totally embedded in the cell walls, some protruded from the cell walls, and others penetrated through the cells. Meanwhile, under the present condition, BF-containing aluminum foams possessed higher compressive strength and energy absorption characteristics than commercially pure aluminum foams, and the reasons were discussed.
Low-cost heat-resistant Al-Sc-Zr-Fe conductor wires were successfully manufactured by continuous rheo-extrusion process, and the mechanical and conductive properties of the materials were analyzed and compared after three different thermo-mechanical treatment methods. The coarse plate-shape Al3Fe phase transformed to small sized rod-like phase after solid solution treatment at 630 °C for 21 h. Direct aging treatment at 300 °C for 24 h led to the refinement and spheroidization of Al3Fe phase with a diameter of 200 nm. After the subsequent aging treatment at 300 °C for 24 h, the tensile strength and conductivity of the alloy wire significantly increased due to the homogeneous precipitation of the coherent spherical Al3(Sc, Zr) phase with an average size of 15 nm. The tensile strength, elongation, and conductivity of the alloy conductor wire after optimized thermo-mechanical treatment reached 165.7 MPa, 7.3%, and 60.26% International Annealed Copper Standard (IACS), respectively. The thermal resistance of the present alloy wire was superior to that of standard AT1 type alloy conductor according to IEC international standard.
This study investigates the presence and distribution of second phases in continuous rheo-extrusion (CRE)-processed Al-La-Ti-B grain refiners and their effect on refining A356 Al-Si alloy. Thermodynamic calculations and microstructural characterization revealed that the main second phases include α-Al, TiAl3, TiB2, Al11La3, LaB6, and Ti2AL20La, with their types evolving with varying Ti/La ratios. The CRE process effectively refined and homogenized these phases. Among the tested refiners, the addition of 0.2 wt.% Al-2.5La-1Ti-1B showed the most effective refinement for A356 alloy, achieving the smallest average α-Al grain size of 221 μm and secondary dendrite arm spacing (SDAS) of 24.62 μm. This optimal refinement corresponded to superior mechanical properties: a tensile strength of 164.52 MPa and elongation of 9.0% in the as-cast state, which were further improved to be 261.13 MPa after T6 heat treatment with elongation of 5.5%. The enhancement is attributed to La’s dual role in modifying the morphology and distribution of TiB2 and TiAl3 phases and acting as a surface-active element to reduce nucleation work, thereby promoting heterogeneous nucleation. This work demonstrates that the CRE process is an effective route to fabricate high-performance La-bearing refiners with engineered microstructures and reveals that optimizing the Ti/La ratio is critical for maximizing grain refinement and mechanical performance in Al-Si alloys.