Materials

In this paper, the effects of rotating magnetic field (RMF) excitation current intensity on Sn segregation, grain refinement, and mechanical properties of Cu-6Ni-6Sn alloy were systematically investigated. The results demonstrate that the application of RMF can effectively refine the as-cast microstructure and mitigate Sn macro-segregation. The average grain size of the as-cast Cu-6Ni-6Sn alloy decreases monotonously with the increase in the excitation current, from 1563 ± 502 μm at 0 A to 207 ± 112 μm at 120 A. In addition, it was found that the difference in Sn content in the radial direction of the ingot reduced from 3.9 wt.% to 1.0 wt.%. The RMF improves heat transfer through forced convection, reduces temperature gradients and alleviates solute enrichment. It increases both thermal undercooling and the growth restriction factor to hinder grain growth and reduces constitutional undercooling to suppress segregation. In addition, the application of the RMF can synergistically increase the tensile strength and the elongation of the as-cast Cu-6Ni-6Sn alloy, with the values changing from 349 ± 4 MPa and 36.9 ± 0.8% at 0 A to 413 ± 4 MPa and 42.8 ± 0.9% at 80 A, respectively. This work quantitatively reveals the coupling relationship between RMF excitation current, grain refinement degree and Sn macro-segregation homogenization in Cu-6Ni-6Sn alloy, and quantitatively clarifies the dominant grain-boundary strengthening mechanism of the alloy under RMF.

In Al–Cu–Mg–Ag sheets considered for aircraft skins, forming and aging alter the state relevant to subsequent fatigue and fracture. Favorable precipitation and tensile responses alone do not establish retention of a specified fracture or fatigue property. This critical narrative review evaluates composition and inherited state, deformation–aging sequence, and separately defined damage endpoints. Documented supplementary searches and evidence mapping support the authors’ engineering and scientific assessment. Chemistry and thermal history jointly control competing precipitates; a smaller Ω volume fraction can coexist with higher yield strength, while resistance to stable tearing can decrease after thermal exposure even when yield strength changes little. Responses to small tensile prestrain, rolling, loading during aging and warm compression depend on the initial state and intervention timing. Tear tests, three-dimensional damage observations, fatigue-life distributions and fatigue-crack-growth measurements reveal distinct roles for particles, boundaries, texture and initiation sites. Cross-over alloys offer bounded comparisons of forming–hardening strategies. The synthesis identifies controls for comparing complete processing routes and locating susceptible regions. Process-retained damage tolerance provides a reporting framework that preserves absolute performance alongside relative change and distinguishes mechanism identification from route optimization. Future work should connect mapped local histories to matched crack endpoints and representative curved structures.

The production of pretensioned concrete elements is significantly influenced by the ability to achieve required bond stress values shortly after the element is formed, which is essential for transferring prestressing force. Due to the complex testing procedure, bond strength is not directly measured in practice. Instead, decisions regarding the transfer of prestressing force to the concrete element are based on the tested compressive strength (typically 30–35 MPa). The literature contains studies and guidelines that define bond strength in normal concretes (generally dependent on the compressive strength of the concrete). Such relationships are lacking for lightweight aggregate concretes (LWAC). CEM I 52.5R is the most commonly used type of cement for prestressed concrete elements due to its rapid strength development. However, concrete with CEM II/A-V 52.5R-NA is characterized by better workability and a lower carbon footprint. This paper presents the results of experimental studies on the bond strength of LWAC made with artificial Certyd aggregate and cement CEM II/A-V 52.5R-NA. The obtained results were compared with results from similar previous studies on LWAC using cement CEM I 52.5R. The analysis encompassed bond stress–slip curves and the correlation between bond strength and free-end slip after 3 and 28 days of curing. The tests conducted and the final analysis of the test results pointed out that Certyd lightweight aggregate concrete made with a concrete mixture with cement type CEM I 52.5R, as well as with cement type CEM II/A-V 52.5R-NA, is appropriate for pretensioned concrete members.