BURA Collection: BCAST is striving for international excellence on both fundamental and applied research on solidification of metallic materials. BCAST sees itself as a reliable source of both new knowledge and new solidification technologies for the metallurgical industry.

低合金化镁合金熔化焊接组织调控的研究进展

2026-04-02T11:08:09Z

Title: 低合金化镁合金熔化焊接组织调控的研究进展 Authors: Zai, L; Tong, X; Wang, Y; Zhang, H; Xue, X Abstract: 摘要：低合金化镁合金因其可加工性好、耐蚀性优异和成本低等优势，成为变形镁合金发展的重要趋势之一。焊接连接已成为推广应用这类材料的关键。然而，低合金化镁合金在焊接过程中存在焊缝晶粒粗大、有效强化相较少等组织软化问题，导致焊接强度不匹配等。本文基于镁合金焊接冶金学的相关理论，重点总结了调控低合金化镁合金焊缝组织的方法，并系统论述了焊缝组织演变过程和机理。最后，针对这类合金在焊接方面的应用需求，对该领域的发展趋势进行了展望。; Due to its advantages, such as good formability, excellent corrosion resistance and low cost, low-alloyed Mg alloys have become one of the important trends in the development of wrought Mg alloys. Welding has become a key method for the widespread application of these materials. However, low-alloyed Mg alloys face the challenges in welding, such as coarse grain structure in the fusion zone and insufficient strengthening phases,leading to mismatched welding strength. This paper, based on relevant theories of Mg alloy welding metallurgy,summarized the methods for controlling the microstructure of low-alloyed magnesium alloy welds, and systematically discussed the evolution process and mechanism of weld microstructure. Finally, in response to the application demands of these alloys in welding, the development trends in this field were prospected.

Rationalisation of steel grades and specifications using machine learning techniques

2026-04-02T13:18:28Z

Title: Rationalisation of steel grades and specifications using machine learning techniques Authors: Sadegh, Jalalian Abstract: There are an excessive number of steel grades currently in use. However, many of them are used in the same application despite differences in chemical composition and processing conditions, and in some cases shows equivalent ranges of properties. These huge number of grades poses challenges for sustainable recycling and increases production complexity and cost. This study introduces a multi-phase, application-driven framework to simplify the steel grade system and reduce the number of grades by proposing a novel approach called K-Means Reduction Process (KMRP). The framework was applied to 148 carbon and 288 stainless steel grades, including chemical composition, processing conditions, and mechanical properties (hardness, UTS, YS, and elongation). Machine learning models were first used to quantify the influence of alloying elements and processing conditions on mechanical performance. K-Means clustering was then applied to group grades based on performance to identify steels that shared equivalent property profiles, with four distinct clusters identified including ferritic/low-carbon steels, medium-carbon and martensitic steels, high-carbon steels, and austenitic steels. These clusters revealed significant redundancy, with multiple grades from existing steel classifications occupying the same mechanical property space. In the reduction phase, KMRP identified the minimal set of grades required to preserve full mechanical property coverage within the generated clusters. Two sustainability-driven strategies were implemented: (1) tramp-element avoidance, favouring grades with low Cu and Sn, and (2) tramp-element tolerance, prioritising grades compatible with scrap-based recycling. While both approaches reduced reliance on critical raw materials (Mo, Ni, V, Ti), this study focused on the tramp-tolerance strategy as the most relevant for advancing circular economy objectives. Under this approach, the number of carbon steel grades were reduced by 38.4% (from 146 to 90) and stainless steel grades by 52.8% (from 288 to 136), while fully preserving the original mechanical property ranges, including UTS ranges of 295–2450 MPa for carbon steels and 120–1970 MPa for stainless steels, and elongation ranges of 7–41% and 2–55%, respectively. These results demonstrated that KMRP can successfully simplify the steel grade system while supporting circularity, reducing dependency on critical elements, and improving the sustainability of future steel production. Moreover, the methodology is generalisable and can be applied to other domains where reducing redundant options is essential, such as pharmaceutical applications. Description: This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London

Mechanism for step-mediated partitioning in Si-Ge rapidly solidified from its parent melt

2026-03-30T02:01:30Z

Title: Mechanism for step-mediated partitioning in Si-Ge rapidly solidified from its parent melt Authors: Al-Jenabi, O; Nassar, A; Cochrane, RF; Mullis, AM Abstract: We investigate the partitioning behaviour of a Si-30 wt% Ge alloy solidified from its parent melt, both close to equilibrium and under rapid solidification conditions. Contrary to the isomorphous equilibrium phase diagram, we observe step-mediated partitioning, with a number of discrete, Ge-rich, compositions occurring in the grain boundary region. The extent of this heterogeneity becomes greater as the cooling rate increases, with little evidence for solute trapping. Three such step-mediated interfaces are investigated using transmission electron microscopy across a range of cooling rates from < 1 s to in excess of 25000 s. Selected area electron diffraction patterns indicate that in all cases the more Ge-rich phase is chemically ordered, again at variance with the equilibrium phase diagram. High-resolution transmission electron microscopy imaging and geometric phase analysis are used to investigate the strain state of these interfaces, leading us to believe that step-mediated partitioning is a means of minimising the lattice strain arising from the atomic size difference between Si and Ge. This is known behaviour in Si-Ge thin films but has gone largely unrecognised in bulk Si-Ge material. Description: Supplementary material is available online at: https://www.sciencedirect.com/science/article/pii/S0925838826016956#sec0060 .

Development of Light Alloys and Their Applications

2026-03-29T02:01:26Z

Title: Development of Light Alloys and Their Applications Authors: Ang, HQ; Kumar, G; Karakulak, E Description: Editorial.