Effect of post‑reaction ultrasonic treatment on synthesis, microstructural evolution and mechanical behaviour of Al 4043/TiB_2 in situ nanocomposites

摘要

Al 4043 is commonly used as a filler material for welding of aluminium-based components. In the present research work,Al 4043/xTiB_2 (titanium diboride) microcomposites (x = 2, 4, 6, 8 and 10 wt%) are fabricated by dilution of Al 4043/10TiB_2in situ master composites synthesized by salt-melt reaction. To synthesize the nanocomposites, in situ Al 4043/10TiB_2 compositesare re-melted, diluted and ultrasonic-treated for 5 min. The microstructural analysis revealed that ultrasonic treatment(UT) is beneficial on improving the dispersion and refinement of TiB_2 particles. UT of Al 4043/2TiB_2 composites reducedthe size of TiB_2 particles from ～ 1270 to ～ 25 nm. At the same time, the efficiency of UT on agglomerate breakage and particlesize reduction decreases with the increase in amount of reinforcement. The hindrance generated by increased amount ofreinforcements to ultrasonic wave propagation and allied impairment on cavitation implosion is proposed as the reason forthe reduction in efficiency of UT. The mechanical property analysis revealed that UT-assisted size reduction and agglomeratebreakage of TiB_2 particles significantly increase both hardness and compressive strength of in situ composites. The resultsrevealed that the compressive strength of TiB_2-reinforced Al 4043/10TiB_2 micro- and nanocomposite increased up to ～ 90 and ～ 150 MPa, respectively. Also, a significant improvement in hardness was observed in the reinforced Al 4043/10TiB_2 micro- and nanocomposites by ～ 94% and ～ 98%, respectively, compared to the monolithic alloy.