Laser powder bed fusion of nano-CaB6 decorated 2024 aluminum alloy

Coated Metal Powders for Laser Powder Bed Fusion (L-PBF) Processing: A Review

“…Gu et al [107] reached a hardness of 188.3 HV0.1 and tensile strength of 486 MPa while the elongation remained constant after coating Al powders with TiC. Mair et al [28], in their study about 2024 Al alloy decorated with CaB 6 , were able to print parts characterized by an equiaxed microstructure, with a relative density of 99.5%, hardness equal to 132 ± 4 HV5, a tensile strength of 391 ± 22 MPa, a yield strength of 348 ± 16 MPa, and elongation equal to 12.6 ± 0.6%. Dong et al [63] noticed that GO sheets applied onto an AlSi10Mg powder partially reacts with the matrix leading to the formation of Al 4 C 3 .…”

“…The general scheme of the ball milling process is reported in Figure 2; the metal powders and the coating particles are inserted into a mill containing the balls and the PCA if needed; the balls lead to a faster homogenization, promoting the adhesion of the coating particles to the powder. Ball milling is widely adopted for coating metal powders to be used in L-PBF [22,23,[26][27][28][29]47,[103][104][105][106][107][108][109][110][111][112][113] and in hot isostatic pressing (HIP) processes [27,114,115].…”

“…In particular, the ball-to-powder ratio ranges from 5:1 to 30:1 in HEBM, whereas it is 1:1 in LEBM [105]. Ball milling is widely adopted for coating metal powders to be used in L-PBF [22,23,[26][27][28][29]47,[103][104][105][106][107][108][109][110][111][112][113] and in hot isostatic pressing (HIP) processes [27,114,115]. According to the energy level, ball milling can be high-energy (HEBM) or low-energy (LEBM).…”

“…These can induce grain refinement mechanisms, thus enhancing the mechanical strength [15,23]. Mechanical properties of the final parts, such as compressive strength [25,26], hardness [15,26,27], yield strength [15,28], and physical properties like density [19,29], are improvable by adopting coated powders.…”

Requirements for Processing High-Strength AlZnMgCu Alloys with PBF-LB/M to Achieve Crack-Free and Dense Parts

“…However, for AA7075 reinforced with 4 ma% TiB 2 µm-particles and processed by using laser metal deposition, an increase in hardness of more than 50% and a decrease of the grain size by 32% were observed [ 29 ]. It can be observed that the vast majority of published studies concerning additive manufacturing of aluminum alloys and changes in the microstructure mainly focus on 6xxx aluminum alloys, two alloying systems like Al-Si alloys with very low hot cracking susceptibility and high-strength aluminum alloys of the 2xxx series [ 3 , 30 ], which can be fabricated free of microcracks and imperfections by powder bed fusion without foreign particles initiating grain refinement [ 31 ].…”