Journal of Materials Science Research and Reviews

Applications of Titanium Alloys, Ni-Based Superalloys, and Aluminum Alloys in Powder Bed Fusion Additive Manufacturing: Process–Microstructure–Property Relationships, Defect Engineering, and Emerging Frontiers

Lv Haiyang — 2026-09-24

Powder bed fusion (PBF) additive manufacturing has emerged as a transformative near-net-shape fabrication technology for advanced metallic components across aerospace, biomedical, energy, and automotive sectors. This review establishes a processing-defect-microstructure-performance tetrahedron framework to systematically evaluate how laser powder bed fusion (LPBF) and electron beam powder bed fusion (EB-PBF) parameters govern the structural integrity and functional properties of six alloy families, with primary emphasis on titanium alloys, nickel-based superalloys, and aluminium alloys, while retaining ferrous alloys, copper alloys, and refractory metals as concise comparative cases. The thermal processing history is examined as the primary control dimension that deterministically shapes defect formation, microstructural evolution, and mechanical performance. Defect mechanisms spanning lack-of-fusion porosity, keyhole porosity, and cracking are analysed through a progressive hierarchy from energy-driven universal phenomena to material-specific manifestations. Microstructural control strategies, including solidification morphology engineering, phase transformation pathway manipulation, and grain boundary design, are synthesised across alloy systems. The mechanical performance hierarchy reveals that Ti-6Al-4V and nickel superalloys deliver the highest specific strength and creep resistance but exhibit greater sensitivity to defect-induced fatigue scatter, while 316L stainless steel and AlSi10Mg offer superior process robustness at moderate strength levels. Advanced characterisation techniques, in-situ monitoring capabilities, and multiscale simulation frameworks are surveyed as essential enablers for process qualification. Emerging frontiers in multi-material architectures, alloy design exploiting non-equilibrium solidification, and industrial scalability are critically assessed, identifying key knowledge gaps and future research directions toward qualification-ready PBF manufacturing.

Research Progress in Fiber-reinforced Microbial Self-healing Concrete

Linfang Liu — 2026-09-26

Fibre reinforcement and microbial mineralisation address different but potentially complementary weaknesses of cementitious materials: fibres limit crack opening and sustain post-cracking load transfer, whereas microbial systems can precipitate mineral phases that obstruct transport pathways and partly restore damaged material. Their integration has therefore been proposed as a route towards concrete that is simultaneously tougher and capable of autonomous crack sealing. This critical narrative review evaluates the research progress in fibre-reinforced microbial self-healing concrete, with emphasis on whether reported benefits constitute demonstrable fibre–microbe synergy rather than parallel effects. Accessible scholarly literature was searched through 17 July 2026 and appraised for mechanistic support, experimental controls, crack-conditioning methods, healing endpoints, durability relevance and translational maturity. The evidence is strongest for polypropylene, polyvinyl alcohol and basalt fibres combined with bacterial carbonate precipitation, with emerging work on steel and natural fibres and on engineered cementitious composites. Fibres can improve healing by restricting crack width, providing bridging surfaces and, for some chemistries, promoting calcium-ion retention or mineral nucleation. Yet optical crack closure, water-tightness and mechanical recovery frequently diverge, and many studies labelled as self-healing primarily measure uncracked strength or matrix densification. Claims of synergy are further weakened by the frequent absence of factorial controls and statistical interaction tests. Encapsulation and carrier technologies improve microbial survival but introduce their own effects on porosity, workability and strength. Laboratory studies support functional recovery under favourable moisture conditions, whereas repeated cracking, realistic aggressive exposures, reinforced-element behaviour and field-scale validation remain limited. The central research need is therefore not simply higher healing percentages, but standardised, mechanism-resolving experiments that connect microbial viability and fibre-controlled crack geometry to transport recovery, structural performance, service-life benefit and life-cycle impact.

Multi-response Optimization of Alkali Treatment and Powdered Bamboo Loading in Epoxy Composites Using Box-behnken Response Surfaces

Innocent Iwara Ibiang — 2026-09-14

Aims: This study developed powdered bamboo/epoxy composites and evaluated the joint effects of sodium hydroxide (NaOH) concentration, treatment time and bamboo loading on mechanical performance and water absorption.

Study Design: A three-factor, three-level Box–Behnken response-surface design comprising 15 runs, including three centre points, was used.

Place and Duration of Study: Department of Mechanical Engineering, University of Cross River State, Calabar, Nigeria; experimental work was completed in 2025.

Methodology: Bamboo powder was treated with 0–15% NaOH for 0–9 h and incorporated into epoxy at 10–20 wt.%. Composites were fabricated by hand lay-up and consolidated under a constant 10 kg load. Tensile, flexural and compressive strengths, Shore D hardness and water absorption were measured. Full quadratic models were fitted in coded variables, and equal-weight desirability optimisation maximised the four mechanical responses while minimising water absorption.

Results: All five models were significant (four at P < .001; water absorption at P = .002), with R² values of .971–.991 and adjusted R² values of .920–.974. The strongest tested formulation, comprising 15% NaOH, 4.5 h treatment and 20 wt.% bamboo, produced tensile, flexural and compressive strengths of 79.576, 103.63 and 89.44 MPa, respectively, with hardness of 43.6 Shore D. Minimum water absorption was 2.78% at 15% NaOH, 4.5 h and 10 wt.% bamboo. The predicted simultaneous optimum was 15% NaOH, 5.68 h and 20 wt.% bamboo, with an overall desirability of .929.

Conclusion: The results demonstrate a strength–moisture trade-off and identify a model-based process window requiring confirmatory validation before structural application.

Improving the Signal of Cell Phones in Places Surrounded by Blocks of Concrete

Mostafa Hassan — 2026-09-17

Dense reinforced-concrete structures can substantially attenuate cellular radio-frequency signals, creating weak-coverage and dead-zone conditions in residential and commercial buildings. This study examines engineering approaches for improving indoor cellular connectivity in concrete-dominated environments while considering signal propagation, system architecture, material selection, and implementation cost. The assessment covers distributed antenna systems, passive repeaters and consumer-grade signal boosters, network-level Wi-Fi calling, small-cell solutions, and RF-friendly construction materials. Link-budget and path-loss expressions are used to describe received power, free-space loss, log-distance attenuation, urban diffraction, building penetration loss, and multi-wall loss. The manuscript also compares active and passive distributed antenna systems in terms of coverage, scalability, signal loss, complexity, and cost, and evaluates network-layer alternatives for situations in which physical modifications are limited. Material-based strategies include low-density or aerated concretes, non-metallic reinforcement, RF-transparent glazing concepts, and non-metallic insulation systems. Bill-of-materials and deployment-cost considerations are presented for selected signal-booster, Wi-Fi-calling, and construction-material approaches. Overall, the analysis indicates that indoor coverage improvement in concrete-rich environments requires a solution matched to the available outdoor signal, building scale, network requirements, and allowable infrastructure changes. The study provides a comparative engineering framework for selecting among active wireless systems, network offloading, and material-based approaches without relying on a single universal intervention.

Investigating the Combined Effect of Cocoa-Pod Husk Ash and Discharged Engine Oil as Admixtures on Strength Properties of Concrete

Amankona Kwame Nyarko — 2026-09-22

The demand for concrete in the construction industry continues to increase. This study examined the performance of concrete modified with discharged engine oil (DEO) and cocoa pod husk ash (CPHA) as admixtures, focusing on physical, mechanical, and durability properties, including density, water absorption, workability, compressive strength, splitting tensile strength, and abrasion resistance. The principal problem is not simply the availability of DEO and CPHA, but the lack of sufficient experimental evidence concerning their combined use as admixtures. This study was conducted at the AAMUSTED Construction Technology and Management Laboratory. CPHA was incorporated at 0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1% by mass of cement, while DEO was added at a constant proportion of 0.066%, using a mix ratio of 1:2:4. The water-cement ratio was 0.55. Concrete specimens were cast and tested after 7, 14, 21, and 28 days of curing to evaluate workability, density, water absorption, compressive strength, splitting tensile strength, and abrasion resistance. At 28 days, the control concrete achieved a compressive strength of 31.08 N/mm², while the mix containing 0.20% CPHA and 0.066% DEO achieved 28.29 N/mm², the highest value among the CPHA replacement mixes. The corresponding splitting tensile strengths were 2.263 N/mm² for the control and 2.204 N/mm² for the 0.20% CPHA mix. At 28 days, the density of the 0.20% CPHA mix was 2414.00 kg/m³. Water absorption was 1.53% for the control and 1.23% for the 0.20% CPHA mix. For abrasion, the control recorded 0.93%, while the 0.20% CPHA mix recorded 1.32%. The study concluded that, although the control specimens generally produced the optimum results, concrete modified with 0.20% CPHA and 0.066% DEO showed the best performance among the CPHA replacement mixes and remained within the reported acceptable performance range for the investigated properties.

Hemp as Bio Fiber Material for Board Paper Applications: Laboratory Evaluation of Handsheets

Klaus Dölle — 2026-09-22

Hemp (Cannabis sativa L.) is one of the oldest fibre crops used in papermaking, predating wood pulp by centuries, and its renewed legal status under the 2014 and 2018 U.S. Farm Bills has revived interest in it as a sustainable papermaking fibre. This study evaluates Hemp fibre as a partial or full replacement for Old Corrugated Container (OCC) recycled fibre in handsheet manufacturing. Hemp stems from Cornell University were processed using two laboratory refining methods - a Kumagai Riki Kogyo Co. (KRK) pressurised refiner and a Sprout Bauer Laboratory Refiner (SBLR) - followed by screening, beating to a common 450 mL Canadian Standard Freeness, and handsheet formation at a target basis weight of 70 g/m². Blends ranging from 100% OCC to 100% Hemp, in 10% increments, were tested for mechanical, structural, and optical properties in accordance with TAPPI standard methods.

The results show that the two refining routes yield markedly different fibre characteristics: KRK-refined Hemp produces denser, less porous sheets with a higher tensile index, whereas SBLR-refined Hemp yields more open, porous sheets with superior burst, tear, and zero-span tensile strength. Blending Hemp into OCC substantially improves tensile index and brightness even at low Hemp content, with an apparent optimal reinforcement window around 20–40% Hemp; beyond roughly 50–60% Hemp, tensile index, elongation, and tensile energy absorption drop sharply and then plateau. Opacity remained near 100% across all blends, brightness increased steadily with Hemp content, and CIE whiteness showed a non-monotonic dip at intermediate ratios. These findings indicate that Hemp is a viable supplementary fibre for recycled paperboard, with the pulping route selected according to target end-use properties, pending further pilot-scale validation.