The use of agricultural residues in alkali-activated composites offers a practical route for waste valorisation, although its environmental benefit requires a complete system-level assessment. This study evaluates treated wheat straw in fly ash-GGBS geopolymer bricks using a 27-run Box–Behnken design. Wheat straw content (0.50–2.00%), fibre length (10–30 mm), NaOH concentration (8–12 M), and GGBS replacement (20–40%) were examined against eight mechanical, physical, thermal, and ultrasonic responses. Measured compressive, flexural, and splitting tensile strengths ranged from 30.2 to 43.3 MPa, 4.74–6.16 MPa, and 2.57–3.31 MPa, respectively. DOE1 (1.25% wheat straw, 20 mm fibre length, 12 M NaOH, and 40% GGBS) produced the highest measured 28-day compressive strength and is identified throughout as the best-performing experimental condition. An equal-weight desirability analysis predicted a compromise at 1.21% wheat straw, 18.4 mm fibre length, 12 M NaOH, and 40% GGBS, with a composite desirability of 0.816. Because this predicted combination was not independently tested, it is presented as a model-derived result within the investigated factor space. All eight quadratic models were significant (p < 0.001); the thermal-conductivity model is used as a screening model because its lack-of-fit was significant. SEM, XRD, FTIR, and TGA/DTA provide qualitative, mutually consistent evidence of differences in matrix morphology, phase features, bonding environments, and mass-loss behaviour, without constituting direct quantitative confirmation of reaction extent or interface chemistry.
Laser powder bed fusion (PBF-LB) of 316L stainless steel produces melt-pool-driven columnar grain structures that result in significant mechanical anisotropy. This study develops a predictive, process-informed 3D geometrically based process-structure (GBPS) framework integrated with crystal plasticity finite element (CPFE) modelling to simulate the tensile response of AM 316L. The framework replaces the need for experimental microstructure data with an idealised, computationally efficient 3D unit cell. Methodological optimisations, including the use of cuboid elements and regularised grain boundaries, achieve a 10-fold reduction in CPU time with negligible ([Formula: see text]) loss in accuracy. The model successfully predicts the characteristic anisotropy of AM 316L, yielding [Formula: see text] higher yield strength and [Formula: see text] higher UTS in the transverse direction compared to the build direction. Furthermore, a defect-sensitivity study reveals that horizontal build orientations are significantly more susceptible to porosity-induced strain localisation, showing a [Formula: see text] drop in ductility at [Formula: see text] porosity. This framework provides a physically motivated yet lean tool for exploring process-structure–property relationships in PBF-LB alloys across varied scanning strategies.
The dissolution behaviour and mechanical properties of bioresorbable Mg-based alloys are strongly governed by their atomic structure: crystalline or amorphous. Amorphous, partially crystalline, and crystalline forms of the biodegradable Mg66Zn30Ca4 alloy were fabricated and their dissolution in phosphate-buffered saline (PBS) and their post-immersion mechanical performance were investigated. Such distinct structures were developed by different cooling rates during solidification. The fully amorphous Mg66Zn30Ca4 alloy exhibited a corrosion resistance comparable to that of commercial Mg-based alloy WE43, while partially crystalline and crystalline counterparts showed accelerated dissolution. Additionally, although as-cast Mg66Zn30Ca4 with different levels of amorphous structure showed a higher compressive strength, all of the Mg66Zn30Ca4 samples lost their strength after immersion, unlike WE43, which remained stable. These materials, therefore, in their current form, do not have the requisite properties for clinical use. The paper demonstrates that structural state plays a critical role in governing dissolution kinetics and mechanical performance in bioresorbable MgZnCa alloys, providing important design considerations for tailoring implant materials. Future prospects for success will need developing an ability to control the volume fraction and spatial distribution of crystalline phases and their morphology.
SiC is a common reinforcement in Al matrix composites, which can improve the mechanical and physical properties. However, the widespread application of Al-SiC composites is limited by the poor wettability of SiC in molten Al. Herein, we investigated the underlying mechanism in A356/SiC composites synthesised by semi-solid stir casting. The microstructure at the interface between the Al matrix and SiC was characterised by SEM and TEM. Microstructural characterisation uniquely identified alumina films at the interface as the critical factor responsible for interfacial cracking and wettability inhibition. The wettability of SiC can be improved when SiC achieves intrinsic contact with Al by removing alumina film during collisions with SiC particles and primary α-Al. Strikingly, the operative wetting mechanism of SiC in molten Al is not lattice mismatch, but rather depends on the chemical nature of the SiC particle surface.
This work presents crystal plasticity finite element (CPFEM) simulations to investigate the grain-scale plastic deformation in an oligocrystalline tantalum specimen subjected to different strain levels, using initial crystallographic orientations derived from electron backscatter diffraction (EBSD) data. A dislocation density-based constitutive model considering the contributions of statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) is employed to describe the evolution of slip resistance during the deformation. The predicted stress–strain response shows reasonable agreement with literature-reported data. The simulations reveal pronounced accumulation of GNDs at grain boundaries, with density decreasing towards grain interiors and increasing systematically with strain. The influence of initial crystallographic orientation on deformation heterogeneity and texture evolution is also investigated and compared with reported data.
