Jamie J Kruzic

UNSW Sydney | UNSW · School of Mechanical and Manufacturing Engineering

The role of microstructure in influencing fatigue crack growth behavior for laser powder bed fusion (LPBF) produced nickel superalloy 718 was examined. Two common post-build heat treatments were applied to produce two distinct microstructures, one which retained much of the solidification structure from additive manufacturing, while the other was m...

Elastostatic compression (ESC) has received considerable research attention as a tool to study rejuvenation and relaxation processes for bulk metallic glasses (BMGs). However, little is understood about the conditions that control whether rejuvenation or relaxation will occur, and whether conditions exist that can give structural stability. We addr...

Human tooth enamel must withstand the cyclic contact forces, wear, and corrosion processes involved with typical oral functions. Furthermore, unlike other human tissues, dental enamel does not have a significant capacity for healing or self-repair and thus the longevity of natural teeth in the oral environment depends to a large degree on the fatig...

Abstracts Quantitatively defining the relationship between laser powder bed fusion (LPBF) process parameters and the resultant microstructures for LPBF fabricated alloys is one of main research challenges. To date, achieving the desired microstructures and mechanical properties for LPBF alloys is generally done by time-consuming and costly trial-an...

Wrought aluminium alloys popular for automotive and aerospace applications are susceptible to solidification cracking when fabricated via laser powder bed fusion (LPBF). Another long-standing and common issue for these alloys is microstructure coarsening and corresponding strength loss caused by elevated temperature exposure. To tackle these challe...

The assessment of the fatigue crack growth rate behavior of welded structural components made of ultra-high strength steels (UHHS) is very important to gain a comprehensive understanding of these materials under high-cycle fatigue loadings and to enhance their applications in the construction industry. The literature on the fatigue crack growth rat...

The extracellular matrix in tissue consists of complex heterogeneous soft materials with hierarchical structure and dynamic mechanical properties dictating cell and tissue level function. In many natural matrices, there are nanofibrous structures that serve to guide cell activity and dictate the form and function of tissue. Synthetic hydrogels with...

Refractory high‐entropy alloys (RHEAs) are candidate structural materials for nuclear applications due to their promising high‐temperature mechanical performance and irradiation tolerance. However, most targeted body‐centered cubic (BCC) RHEAs form additional phases depending on their thermal history, and studies investigating the effect of these p...

AlSi10Mg alloy modified with 4 wt.% cerium was fabricated by selective laser melting and subjected to a T6 solutionizing (2 h at 535°C) and ageing (10 h at 160°C) heat treatment. Microstructure, precipitates and hardness of as-built and heat-treated samples were analysed. Results show that as-built samples contained a refined cellular-dendritic mic...

Platinum-based electrocatalysts possess high water electrolysis activity and are essential components for hydrogen evolution reaction (HER). A major challenge, however, is how to break the cost-efficiency trade-off. Here, a novel defect engineering strategy is presented to construct a nanoporous (FeCoNiB0.75 )97 Pt3 (atomic %) high-entropy metallic...

Ni-Nb-based bulk glass-forming alloys are among the most promising amorphous metals for industrial applications due to their incomparable combination of strength, hardness, elasticity and plasticity. However, the main drawback is the limited glass-forming ability, narrowing the field of application to solely small components. In this study, we show...

Pair distribution function (PDF) analysis is a powerful technique to understand atomic scale structure in materials science. Unlike X-ray diffraction (XRD)-based PDF analysis, the PDF calculated from electron diffraction patterns (EDPs) using transmission electron microscopy can provide structural information from specific locations with high spati...

Chitosan particles loaded with dibasic calcium phosphate anhydrous (DCPA) is a promising strategy for combining antimicrobial and osteoconduction properties in regenerative medicine. However, mostly micrometer-sized particles have been reported in the literature, limiting their use and reducing their effect in the biomedical field. We have recently...

Of the various metal additive manufacturing methods, wire-arc directed energy deposition (DED) enables processing large components at relatively high deposition rates with low raw material costs and has the ability for in-situ alloying materials to achieve chemical gradients. Here, we investigate micro and mesostructure, and corresponding mechanica...

The accurate prediction of elevated-temperature creep behaviour of alloys is important for preventing catastrophic failure of systems operating under prolonged elevated temperature-stress conditions. Here, we couple the Kachanov-Rabotnov (K-R) creep model with a multi-objective genetic algorithm (MOGA) to predict the creep behaviour of Alloy 617 at...

This study presents incremental finite element computations of creep‐fatigue crack growth in Alloy 718 at 650°C$$ 65{0}^{{}^{\circ}}\mathrm{C} $$ in air. Alloy 718 is representative of creep‐brittle materials, in which viscoplastic deformation is restricted near the tip of a growing crack. The computations predict crack growth using a unique combin...

The demanding operating environments of advanced nuclear reactors require the development of new nuclear materials that can withstand their increased physical, chemical, thermal, and radiation-related challenges. High-entropy alloys (HEAs) have shown often-impressive mechanical, thermomechanical, and corrosion-resistant properties, and offer a mass...

Zr-based bulk metallic glasses (BMGs) are amorphous alloys that can exhibit excellent mechanical properties, including high yield strength and fracture toughness. These properties are linked to local microstructural heterogeneities. Whether via microscopy-based techniques, synchrotron techniques, or calorimetric approaches, the amorphous structure...

Many industries such as aerospace, power generation, and ground transportation demand structural materials with high specific strength at elevated temperatures. Up until now, many types of heat‐resistant materials including Ni‐based superalloys, intermetallic compounds, and dispersion‐strengthened alloys have been developed for specific application...

A new type of high-entropy alloy with a composition of Pt 25 Pd 25 Ni 25 P 25 (at.%) and an amorphous structure, referred to as a high-entropy metallic glass (HEMG), was developed by a scalable metallurgical technique for efficient hydrogen evolution reaction (HER). The achieved overpotential was as low as 19.8 mV at a current density of 10 mA cm −...

Engineering materials processed using additive manufacturing (AM) techniques such as laser powder bed fusion (LPBF) often exhibit unique microstructures and defects that must be controlled to obtain peak performance in mechanical properties. Towards this end, we here investigate how three heat-treatments (direct aging, solution treatment + aging, a...

Multi-principal element alloys (MPEAs) have attracted rapidly growing attention from both research institutions and industry due to their unique microstructures and outstanding physical and chemical properties. However, the fabrication of MPEAs with desired microstructures and properties using conventional manufacturing techniques (e.g., casting) i...

Additive manufacturing of bulk metallic glasses (BMGs) has opened this material class to an exciting new range of potential applications, as bulk-scale, net-shaped amorphous components can be fabricated in a single step. However, there exists a critical need to understand the structural details of additive manufactured BMGs and how the glassy struc...

The effects of build orientation and hot isostatic pressing (HIP) were examined for CP-Ti manufactured from grade 2 commercially pure titanium powder using laser powder bed fusion (LPBF). Two orthogonal build orientations were combined with two HIP treatments, one above (950°C) the β-transus temperature and one below (730°C). Cracks tended to grow...

Water is a crucial component of bone, affecting the interplay of collagen and minerals and contributing to bone’s high strength and ductility. Dehydration has been shown to significantly effect osseous mechanical properties; however, studies comparing the effects of various dehydrating environments on fracture toughness of bone are scarce. Accordin...

Bulk metallic glasses (BMGs) naturally have excellent strength and elasticity while structural rejuvenation into higher energy glassy states is often required to improve ductility. However, our understanding of the detailed atomic ordering changes that occur during rejuvenation processes, such as plastic deformation, remains limited. This study uti...

The anisotropic mechanical properties of ultrasound freeze cast epoxy-ceramic composite materials were studied by measuring flexural strength and fracture resistance curves (R-curves) using both unnotched and notched three-point beam bending experiments, respectively, cut in three different orientations relative to the directional freezing axis. Th...

A Gaussian process regression-based machine learning approach was used to establish a processing window optimized for high density additive manufacturing of a 2 vol.% TiCN reinforced AlSi10Mg composite by laser powder bed fusion. The optimized window for TiCN reinforced AlSi10Mg was found to be smaller than for AlSi10Mg. Within the optimized window...

Anticipating an increasing demand for hybrid double network (DN) hydrogels in biomedicine and biotechnology, this study evaluated the effects of each network on the mechanical and biological properties. Polyethylene glycol (PEG) (meth)acrylate hydrogels with varied monomer molecular weights and architectures (linear vs. 4-arm) were produced with an...

Both uniform and graded gyroid cellular structures (GCSs) of NiTi have been successfully fabricated by laser powder bed fusion (LPBF) additive manufacturing. NiTi GCSs were produced with gradients along two different directions , and the surface morphology and mechanical properties of different GCSs were systematically studied using micro-x-ray com...

A key problem in fatigue crack growth is the influence of load transients, such as overloads, on crack growth rates. This has been investigated in detail for materials operating near room temperature but is less well understood at high temperatures, where rate dependence becomes important. Here, finite element computations using an elastic-viscopla...

A high strength Al-5024 alloy containing Sc and Zr with a bi-modal microstructure consisting of fine equiaxed and coarse columnar grains was successfully fabricated by laser powder bed fusion (LPBF) additive manufacturing. The formation of the bi-modal microstructure was mainly due to both the formation of primary Al3Sc precipitates that act as nuc...

The influence of strain rate across three orders of magnitude (1.70 × 10⁻⁵ /s to 1.43 × 10⁻² /s) along with the effect of the plastic strain accumulation (up to 10%) on the serrated plastic flow were investigated in the nickel-chromium (Ni-Cr) solid solution alloy Nimonic 75 by performing constant-strain-rate tension testing at 600°C. As the strain...

Single phase high-entropy alloys (HEAs) are often assumed to be random solid solutions with homogeneous elemental distributions. This may not always be true and atomic arrangements and chemical homogeneity depend on the processing history of the material. In this study, electron probe microanalysis (EPMA) and atom-probe tomography (APT) were perfor...

High-Entropy Metallic Glass In article number 2101586, Ligang Sun, Jian Lu, Jamie J. Kruzic, and co-workers develop a high-entropy metallic glass using a scalable metallurgical technique. Dealloying creates a nanosponge-like architecture with embedded nanocrystals that provide abundant active sites to achieve outstanding hydrogen evolution activity...

Background and Aims The purpose of this investigation was to test the hypothesis that a novel adhesive retention suture device (ARSD) can increase perfusion at elliptical wound closures by distributing stress away from the suture site. Methods Stress in the skin around a suture both with and without support from an ARSD was evaluated using a finit...

The incorporation of mechanosensitive linkages into polymers has led to materials with dynamic force responsivity. Here we report oxanorbornadiene cross-linked double network hydrogels that release molecules through a force-mediated retro Diels-Alder reaction. The molecular design and tough double network of polyacrylamide and alginate promote sign...

The effects of build orientation and post heat treatments on the tensile and fatigue crack growth (FCG) behavior of commercially pure titanium (CP-Ti) manufactured by laser powder bed fusion (LPBF) using grade 2 powder were examined. Two orthogonal build orientations were used in conjunction with hot isostatic pressing (HIP) both above (950°C) and...

In this paper, a novel approach is presented to tailor the stress properties of diamond thin films via boron doping and micro-fabrication of bridges using focused ion beam milling. The experimental data, based on detailed confocal micro-Raman investigations, are supported and interpreted through finite element method calculations of the stress dist...

High strain rate micromechanical testing can assist researchers in elucidating complex deformation mechanisms in advanced material systems. In this work, the interactions of atomic-scale chemistry and strain rate in affecting the deformation response of a Zr-based metallic glass was studied by varying the concentration of oxygen dissolved into the...

The mechanical performance of a Ni–Mo–Cr (GH3535) alloy weldment, produced using a matching filler metal, was assessed and compared to the surrounding parent metal. Ambient-temperature mechanical characterisation included hardness testing, small punch testing and uniaxial tensile testing, while a crystal plasticity finite element model was used to...

The combination of refined microstructures (induced by rapid cooling) and melt pool-induced mesostructures in AlSi10Mg fabricated using laser powder bed fusion (LPBF) – a widely used additive manufacturing technique – impart high strength and fracture toughness. Further exploitation of such property combinations requires a detailed understanding of...

Developing highly efficient and durable electrocatalysts for hydrogen evolution reaction (HER) under both alkaline and acidic media is crucial for the future development of a hydrogen economy. However, state‐of‐the‐art high‐performance electrocatalysts recently developed are based on carbon carriers mediated by binding noble elements and their comp...

In this study, two sets of optimized laser powder bed fusion (LPBF) additive manufacturing parameters with similar energy density but different laser powers (HP: high laser power with high scanning speed, LP: low laser power with low scanning speed) were used to produce fully dense and crack-free NiTi samples. The microstructure, phase transformati...

This short communication presents 2 - 4 μm sized TiCN reinforced AlSi10Mg composites (TiCN/AlSi10Mg) fabricated by laser powder bed fusion (LPBF) with refined Al-Si eutectic microstructure consisting of equiaxed bi-modal α-Al grains and enhanced elevated temperature tensile strength. The formation mechanism of reported bi-modal structure is related...

Bulk metallic glasses (BMGs) are materials with outstanding strength and elastic properties that make them tantalizing for engineering applications, yet our poor understanding of how their amorphous atomic arrangements control their broader mechanical properties (hardness, wear, fracture, etc.) impedes our ability to apply materials science princip...

Dynamic cell culture materials that can change mechanical properties in response to extrinsic stimuli are emerging as promising tools for cell and tissue engineering research. However, most of these techniques involve a one‐way stiffening or softening through changes in the materials chemistry, which does not allow reversibility. Here we demonstrat...

Effects of build orientation (0°, 45°, 90°) and post heat treatments (hot isostatic pressing 820 °C, 950 °C or annealing 1020 °C) on the fatigue crack growth rates (FCGRs) of Ti-6Al-4V fabricated by laser powder bed fusion were examined. Coarser α′/α lath thicknesses resulted in slower FCGRs and higher fatigue thresholds while texture and build ori...

Laser additive manufacturing of bulk metallic glass (BMG) provides an effective bypassing of the critical casting thickness constraints that limit the size of components that can be produced; however, open questions remain regarding the resulting mechanical properties. In this work, a Zr-based glass with composition Zr59.3Cu28.8Nb1.5Al10.4 was prin...

Machine-learning assisted laser powder bed fusion process optimization for AlSi10Mg: New microstructure description indices and fracture mechanisms, Acta Materialia (2020), doi: https://doi. Abstract In this study, a machine-learning approach based on Gaussian process regression was developed to identify the optimized processing window for laser po...

Objectives Understand how discontinuous short glass fibers and braided long fibers can be effectively used to reinforce a resin modified glass ionomer cement (RMGIC) for carious lesion restorations. Methods Two control groups (powder/liquid kit and capsule) were prepared from a light cured RMGIC. Either discontinuous short glass fibers or braided...

This study aims to assess the accuracy of various modelling methodologies in predicting creep-fatigue damage (dcf) and cycles-to-crack-initiation (Ni) of Alloy 617 at 850 °C and 950 °C. In the decoupled methodologies, four creep damage models were employed: (i) the time fraction (TF), (ii) ductility exhaustion (DE), (iii) stress-modified ductility...

Metallic glasses (MGs) with superior catalytic performance have recently been recognized as attractive candidates for wastewater treatment. However, further improving their performance will require knowledge of how to precisely regulate their electronic structures via compositional control. Here, two Fe-based MGs (Fe78Si9B13 and Fe80Si9B11) were pr...

In order to understand the fracture toughness anisotropy of avian eggshells, we have investigated eggshells of the emu (Dromaius novaehollandiae) whereby the large size (∼13 cm × 9.5 cm) enabled the fabrication of beam samples in various orientations. The emu eggshell was found to have a hierarchical microstructure similar to chicken eggshell, with...

Some natural materials, such as the dactyl club of the mantis shrimp, have impressive mechanical properties (e.g. strength) due to their microstructure that consists of periodic layers of high and low density material, which prevent crack propagation. Although such layered structures have the potential to increase the strength of engineered epoxy-c...

An irreversible cohesive zone model was used to understand how plastic strain gradients and yield strength mismatches affect fatigue crack growth across bi-material and multilayer interfaces for a range of interface strengths. Parametric studies identified regimes of penetration through the interface, deflection into the interface, and a transition...

Shear bands were introduced into a Zr–Ti–Cu–Ni–Al bulk metallic glass (BMG) by one-directional cold rolling and the effect on fracture toughness anisotropy was examined. Two different rolling and shear band orientations relative to the crack plane were used, with the rolling force oriented along either the width (CR-W) or thickness (CR-T) direction...

In article number 2000385, Jian Lu, Chain Tsuan Liu, and co‐workers develop a novel multinary high‐entropy intermetallic (HEI) with an unusual periodically ordered structure and multiple low‐cost elements that present superior water‐splitting performance in both efficiency and stability when compared to the current state‐of‐the‐art systems. The exc...

Although metallic glasses (MGs) with unique disordered atomic structure have increasingly attracted great research interest as one of the most innovative heterogeneous catalysts in water remediation, few works focused on the synergistic role of different elemental constituents to well understand their superb catalytic performance. Herein, Co atoms...

Electrochemical water splitting offers an attractive approach for hydrogen production. However, the lack of high‐performance cost‐effective electrocatalyst severely hinders its applications. Here, a multinary high‐entropy intermetallic (HEI) that possesses an unusual periodically ordered structure containing multiple non‐noble elements is reported,...

Porous Fe3O4 scaffolds were fabricated while subject to a low (7.8 mT) magnetic field applied in helical and Bouligand motions using a custom-built tri-axial nested Helmholtz coils-based freeze-casting setup. This setup allowed for the control of a dynamic, uniform low-strength magnetic field to align particles during the freezing process, resultin...

The incorporation of antimicrobial agents in restorative dental composites has the potential to slow the development of carious lesions. Objective: The objectives of the present study were to develop experimental composite resins with chitosan or chitosan loaded with dibasic calcium phosphate anhydrous (DCPA) particles and to demonstrate their an...

The molten salt corrosion performance of a Ni–Mo–Cr (GH3535) alloy weldment, produced using matching filler metal, was assessed. Corrosion testing was performed in FLiNaK molten salt at 750 oC for 500 h. Present results reveal that, despite a similar chemical composition, the weld metal has somewhat superior corrosion resistance to the parent metal...

Shape-memory materials (SMMs) are characterized by their unique ability to remember and recover their shape in response to external stimuli. Over recent decades, the use of SMMs in biomedical areas such as tissue engineering, drug delivery, endovascular surgery, orthodontics, orthopedics, etc. has attracted significant attention from both academia...