科研之友
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摘要
With a broad freezing range and a high content of alloy elements, 2024 prepared by selective laser melting still has some defects like hot tearing and columnar grains. In this work, TiB2/2024 composite powders with different nanoscale TiB2 contents were prepared by low-energy ball milling and used for selective laser melting process. The effects of TiB2 content on the phase, microstructure and mechanical properties of 2024 aluminium alloy were studied by means of X-ray diffraction, metallographic microscope, EBSD and SEM. The results show that the addition of 1% nano-TiB2 makes the coarse columnar grains transform into equiaxed grains, and improve density of SLM samples the grain size decreases from 19.9 μm to 4.25 μm and the relative density increases from 97.3% to 98.2%. Tensile strength, elongation and micro-hardness increase by 23%, 208% and 5.1%, respectively. Furthermore, tensile strength and elongation reach 401.2 MPa and 10.4% respectively at T6 state. When the mass fraction of TiB2 increases to 3%, the refining effect is weakened to 3.97 μm, and the agglomeration of nano-TiB2 grew to micron-scale. The density and comprehensive mechanical properties of the samples decreases sharply. ? 2019, Editorial Office of Materials Science and Engineering of Powder Metallurgy. All right reserved.
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