Effect of ultrasound in the bonding process of MB8/Cu/2024 dissimilar alloys by Yinan LI, Xiaoxuan YUAN, Dingwen SHI, Zilong PENG

“…And under the influence of shear stress, This displacement could lead to interfacial friction, resulting in the removal of Al and Cu particles and partial removal of the oxide film. in the solid/liquid transformation stage, 2024/Cu interface produced a temperature rise due to friction under the action of ultrasound, and Al2Cu + α-Al liquid phase began to appear after the eutectic reaction temperature was reached; In the liquid/liquid interface reaction stage, cavitation and acoustic streaming effects made MB8/Cu and 2024/Cu interfaces generate z-direction displacement field and acoustic pressure field, accelerating generation of Al2Cu + α-Al and Mg2Cu + α-Mg eutectic phases to form joining. the maximum shear strength of the MB8/2024 dissimilar metal joints was 64 MPa.…”
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A PAIR OF FOUR-ELEMENT HORIZONTAL GENERATING SETS OF A PARTITION LATTICE by Gábor Czédli

“…Our main goal is to construct four partitions of a finite set \(A\) with \(n\geq 7\) elements such that each of the four partitions has exactly \(\lceil n/2\rceil \)  blocks and any other partition of \(A\) can be obtained from the given four by forming joins and meets in a finite number of steps. …”
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