The effect of the TiC-TiB2 nanoparticles on the microstructure and mechanical properties of Al-Mn-Si strips fabricated by twin-roll casting

Abstract

In this work, Al-Mn-Si and TiC-TiB2/Al-Mn-Si strips were prepared by vertical-type twin-roll casting (TRC), and the effect of TiC-TiB2 nanoparticles (NPs) on the microstructure and mechanical properties of TRC Al-Mn-Si strips were studied. The TRC strips had the characteristics of coarse grains near the surface and fine grains in the center. The introduction of NPs resulted in the formation of uniform and fine grain structures due to the grain refinement effect of NPs. The refining effect on the surface grains was much greater than that on the central grains because the larger thermal undercooling of the melt at the surface led to the improvement of the nucleation efficiency of NPs. TiC-TiB2 particles could eliminate the central segregation of TRC Al-Mn-Si strips due to the control of solute diffusion by the uniform and fine grain structures, thereby reducing α-Al(Mn, Fe)Si formation in the central region. The mechanical properties of the TRC Al-Mn-Si strips were improved with the introduction of NPs. The yield strength at room temperature was increased from 79.0 MPa to 92.9 MPa, and the uniform elongation was increased from 7.2% to 10.1%, due to the fewer eutectic α-Al(Mn, Fe)Si, refined precipitates and grain structures caused by the addition of the TiC-TiB2 particles.