Institute of New Materials

The influence of pre-deformation on the microstructure and mechanical properties of a Mg-rich high-Cu Al-Mg-Si-Cu alloy was systematically investigated by hardness measurement, tensile test, and atomic resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). With the increase in pre-deformation strain (0–10%), the hardness and strength of the alloy after PB hardening increased progressively, accompanied by a continuous reduction in tensile elongation. Notably, increasing pre-deformation strain from 2% to 10% did not bring a significant enhancement in bake hardening response, despite the gradual improvement in the strain hardening capability of the alloy. An optimal pre-deformation strain of 5% is identified, which enabled the alloy to achieve a superior and industrially feasible combination of strength and ductility, balancing practical forming demand (T4 temper) and service performance (PB state). Pre-deformation can significantly affect the morphology and atomic structure of precipitates for the alloy. Dislocations introduced by pre-deformation acted as heterogeneous nucleation sites, inducing the formation of elongated and string-like precipitates along dislocation lines. A distinct Cu segregation behavior was observed in the pre-deformed alloy with the majority of Cu atoms segregated at the precipitate/α-Al interface, which was in sharp contrast to their dominant distribution within the precipitate interior in the non-pre-deformed alloy. These findings provide new insights into deformation-assisted precipitation regulation in Mg-rich high-Cu Al-Mg-Si-Cu alloys and offer practical guidance for optimizing the strength–ductility synergy of such alloys for automotive lightweight manufacturing applications.

To promote the effective recycling of waste ceramic tiles and alleviate the shortage of natural river sand, this study systematically investigates the strength and durability of concrete incorporating recycled ceramic fine aggregate (RCFA), herein referred to as RCFA concrete, at water-to-binder (W/B) ratios ranging from 0.25 to 0.45. The RCFA was produced by crushing waste ceramic tiles characterized by low water absorption. As indicated by experimental results, RCFA concrete exhibits improved compressive strength and enhanced resistance to freeze–thaw cycles and chloride ion penetration compared to natural aggregate concrete. However, the beneficial effects of RCFA diminish at lower W/B ratios. Furthermore, the incorporation of RCFA significantly reduces autogenous shrinkage and alleviates the decline in internal relative humidity, with these effects being more pronounced at lower W/B ratios. Conversely, RCFA increases drying shrinkage at the W/B ratio of 0.45, although this negative effect is mitigated as the W/B ratio decreases. Mercury intrusion porosimetry and scanning electron microscopy analyses reveal that RCFA improves concrete performance by reducing microporosity and enhancing the interfacial bonding between fine aggregates and hydration products.

ABSTRACT Laser‐enhanced contact optimization (LECO) technology has attracted growing attention to further improve the photovoltaic conversion efficiency (PCE) of tunnelling oxide passivated contact (TOPCon) solar cells. Although LECO is known to improve metallization via current‐induced firing, the specific interaction between interfacial microstructure evolution, contact resistance, and carrier recombination remains not fully understood. Herein, we clarify the underlying mechanisms of silver‐silicon contact formation on the p + emitter during fast firing and subsequent LECO processing. We identify that a relatively low peak firing temperature followed by a secondary LECO treatment is more promising than increasing the firing temperature. Specifically, while the secondary LECO process leads to a slight increase in localized specific contact resistivity, it significantly increases the areal density of effective Ag–Si contact points, including Ag–Si alloy. This increased contact density compensates for the local resistivity rise through a parallel resistance network mechanism, ensuring efficient carrier extraction. Furthermore, unlike high‐temperature firing, which aggravates passivation damage, the secondary LECO acts as a localized annealing process, simultaneously minimizing metal‐induced recombination. Consequently, this optimized strategy endows the champion cell achieving a PCE of 26.69%. This work provides critical insight into balancing carrier transport and recombination, offering a promising route toward the development of high‐efficiency TOPCon solar cells.

Abstract The characteristics of the pigments and the composition of the formulation have a decisive influence on the appearance of coloured plastics, mainly in terms of their reflectance and transmittance. This research presented a novel analytical approach to quantify the optical properties of pigments and predict the appearance of plastics containing these pigments accordingly. Firstly, the Monte Carlo method was employed to characterise the measurement geometry of the spectrophotometer and the light transfer in coloured plastics. Based on this, the paper proposed a method for determining the absorption coefficients and scattering coefficients of the substrate and the pigments according to reflectance and transmittance measurements. To verify the efficacy of the approach, 25 polyethylene‐based samples were prepared. The samples 1–15 were used to determine the optical properties of the respective pigments, and the samples 16–25 to test the predictive capabilities of the model. The result showed that the method can reliably predict the reflectance, transmittance and colour of plastic formulations.

To optimize the mix proportion and technological conditions for preparing geopolymer non-fired bricks from burned coal gangue, addressing issues such as high energy consumption, large clay resource consumption in traditional brick-making industries, and environmental pollution from coal gangue and calcium carbide slag stockpiles, this study constructs a binary geopolymer system of coal gangue-calcium carbide slag. Through orthogonal experimental design, the effects of alkali content, calcium carbide slag dosage, forming pressure, water-to-solid ratio, and initial curing temperature on the compressive strength and water absorption rate of bricks were systematically investigated. The micro-mechanism of the geopolymerization reaction was revealed by SEM, XRD, and FTIR. The results show that burned coal gangue exhibits significant silico-alumino activity under NaOH activation, with the 28-day compressive strength of single-component bricks reaching 8.9 MPa. Introducing calcium carbide slag can synergistically improve performance, with the best effect achieved at a dosage of 20%, where the compressive strength of bricks increases by 286.5% compared to pure coal gangue samples. The optimized process parameters are determined as follows: alkali content 9%, calcium carbide slag dosage 20%, water-to-solid ratio 15%, forming pressure 15 MPa, and initial curing temperature 50°C. Under these conditions, the brick’s compressive strength reaches 34.4 MPa, and water absorption rate is 5.6%, meeting the requirements of JC/T 422-2007 standards. This study provides a low-cost and high-benefit engineering path for the high-value utilization of coal-based solid waste, demonstrating significant practical significance for promoting the development of green building materials and circular economy.