Microstructure and mechanical properties of Ti-B₄C/Al2024 composite with hybrid structure

Abstract

In order to study the effect of hybrid structure on the mechanical properties of aluminum matrix composites. The gas-atomized Al2024 powders were mechanically blended with Ti-10% (mass fraction) B4C powders by ball milling for different time, and then compacting the powders via hot press sintering and hot extrusion to fabricate the hybrid structured Ti-B4C/Al2024 composite. The microstructure and mechanical properties of different materials were observed and tested by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile testing machine. The strengthening and toughening behavior of hybrid structured composites were further discussed. The results show that the hybrid structured Ti-B4C/Al2024 composite consists of Al2024 matrix, core-shell structured Ti/Al18Ti2Mg3 and B4C particles. With the addition of 5% Ti-B4C hybrid powder after ball milling for 6h, the yield strength increases from 107MPa to 122MPa, and the composite exhibits almost the same elongation as that of the hot extruded Al2024 alloy. When the milling time is extended to 12h, the elongation of the sample 5TB-12h can reach 16.4%. However, the elongation of the composites decreases with the increase of Ti-B4C.

Keywords

• metal matrix composites
• aluminum alloy
• hybrid structure
• mechanical property