Jacob Huang

National Sun Yat-sen University | NSYSU · Department of Materials and Optoelectronic Science

The traditional approaches for improving corrosion resistance of alloys typically lead to the sacrifice of mechanical properties because the microstructures needed for improving corrosion resistance often contradict those for high strength. Here we demonstrate that selected laser melting (SLM), a net-shape additive manufacture technique, can mainta...

Homogeneous NiCo2O4 (NCO) microspheres encapsulated by holey graphene framework (HGF) are synthesized by using solvothermal and further annealing approaches, respectively. By tuning the solvothermal conditions involved in the synthesis process, the specific oxygen vacancies induced into NCO microspheres with different ratios can be researched compr...

A single-phase bimodal grain structure is considered to develop a physical model to quantify hetero-deformation induced (HDI) strengthening at the yield point, which cannot be simply predicted by the conventional rule-of-mixtures using the Hall-Petch equation. Based on the classic theory of single-ended continuum dislocation pileup, the modified mo...

For metallic materials, it is challenged to enhance the strain hardening rate under uniaxial tension when high flow stress is achieved. Here, we present a strategy enabling to obtain superior strain hardening ability via fabricating an incompletely recrystallized structure in a precipitation-strengthened Co-rich CoCrNiAlTi medium-entropy alloy. It...

In this study, a thermodynamically metastable medium-entropy Co37Cr34Ni29 (at.%) alloy exhibiting superior strength-elongation synergy at ambient temperature was fabricated successfully via tailoring the processing route. It was discovered that after homogenizing and hot-rolling processes, the microstructure of the alloy was composed of two-type fa...

Lightweight Ti65(AlCrNb)35 medium-entropy alloy (Ti-65) ingots were produced through arc melting and drop casting in a water-cooled copper mold. These alloy ingots were then treated through a sequence of homogenization, hot rolling, cold rolling, and recrystallization. The effect of this thermomechanical treatment (TMT) on their microstructures and...

High entropy alloys (HEAs) have attracted significant interest in recent decades due to their unique microstructures and many favorable properties, including high mechanical strength, good thermal stability and excellent corrosion resistance. In the present study, three Cu-Al based medium entropy alloys (MEAs), namely CuAlAg (CAA), CuAlZn (CAZ) and...

The microstructure and passivation behavior of the Ti-Ta-Nb medium-entropy alloy (MEA) films prepared by sputtering were investigated. The Ti-Ta-Nb MEA films show significantly improved corrosion resistance compared to pure Ti in 0.5 M H2SO4. The mechanisms of the passivation behavior and stability of the passive films were extensively explored and...

Nanoporous silver (NPS) with a three-dimensional (3D) bicontinuous ligament/pore structure can be fabricated in different ways and with different treatments. Thermal treatments before or after dealloying can have a considerable impact on the dealloying process. High-temperature oxidation (HTO) has been researched as a method to tune the process of...

Using the CALPHAD method, lightweight nonequiatomic Ti60(Al)x(VCrNb)40-x (x = 6, 8, 10, 12, and 18 at.%) medium-entropy alloys (MEAs) were designed and produced using vacuum arc melting and drop casting. The density of these cast alloys decreased with an increase in Al concentration from 5.45 to 4.79 g cm⁻³. All of these cast alloys exhibited a bod...

Ag50Cu50 films were deposited on glass substrates by a sputtering system. Effects of accumulated energy on nanoparticle formation in pulse-laser dewetting of AgCu films were investigated. The results showed that the properties of the dewetted films were found to be dependent on the magnitude of the energy accumulated in the film. For a low energy a...

The focus of this study was the design of implants related to the tibia bone. Most of the pressure loads applied on the tibia bone by the human body are normal forces. An orthogonal structure has been introduced in porous implants because it can support higher normal stress than other porous structures. Human bone is composed of an outer cortical b...

AgCuAl equimolar complex concentrated alloy (CCA) thin films are deposited on glass substrates using a high-vacuum sputtering system. The films are annealed at 400oC for 5 minutes to stabilize the structure and are then dewetted using a NIR pulsed-laser system at various pulse powers, repetition rates and scan speeds to form nanoparticles. It is sh...

Eutectic multi-principal element alloys exhibit homogeneously fine microstructure, excellent castability and good industrial application prospect. In this work, the microstructure and mechanical properties of (FeCoNi)100-x(NiAl)x eutectic multi-principal element alloys are studied. The phase constitution of the studied FeCoNiAl systems is FCC+B2 Ni...

The incipient plasticity and creep behavior of body-centered cubic (BCC) Ti65(AlCrNb)35 medium entropy alloy (MEA) were investigated via nanoindentation. The elastic modulus and hardness obtained from different methods were compared. The activation volume for plastic deformation was calculated to be 11 b³, indicating a larger-scaled Peierls deforma...

Alloys that have high strengths at high temperatures are crucial for a variety of important industries including aerospace. Alloys with ordered superlattice structures are attractive for this purpose but generally suffer from poor ductility and rapid grain coarsening. We discovered that nanoscale disordered interfaces can effectively overcome these...

Alloys with ultra-high strength and sufficient ductility are highly desired for modern engineering applications but difficult to develop. Here we report that, by a careful controlling alloy composition, thermomechanical process, and microstructural feature, a Co-Cr-Ni-based medium-entropy alloy (MEA) with a dual heterogeneous structure of both matr...

There are overwhelming experimental observations indicating intermetallic (IM) phase formed in the intermediate temperatures in high entropy alloys. In this study, we proposed a model to show how kinetics could intervene the thermodynamic determination of phase formation. The model offers a good explanation for the prevalent formation of IM formati...

Some high or medium entropy alloys (HEAs and MEAs) have been demonstrated to exhibit great mechanical and bio-corrosion properties to meet the demands as bio-implant materials. However, the difference in Young’s modulus between these alloys and human bone would induce stress shielding effects. Therefore, HEA or MEA coating films appear to be potent...

A series of porous toxic-element-free Ti42Zr40Si15Ta3 bulk metallic glass with 13–54 vol.% porosity are produced via powder metallurgy by the space holder method. The amorphous nature, foam morphology, mechanical properties, electrochemical response in simulation body fluid and in-vivo biocompatibility responses are systematically investigated. Res...

In the present study, a Co-rich CoCrNi-AlTi high-entropy alloy was designed and fabricated by hot forging and 700 °C for 8 h annealing process. The microstructure of the resultant alloy was composed of three multicomponent-phases with the face-centered cubic (FCC) structure, hexagonal close-packed (HCP) structure and L1 2 structure, respectively. T...

Due to the demand for reduced energy consumption by transportation vehicles, lighter weight high-entropy alloys (with density comparable to that of commercial Ti alloys around 4.5–5 g/cm³) are attracting more attention in terms of alloy design and application as structural materials. In this study, a nonequiatomic quaternary alloy system, Tix(AlCrN...

Pure Cu and Cu80Zr20 thin films with a thickness of 10 nm were deposited on glass substrates using a high-vacuum sputtering system. A pulsed-laser dewetting process was then performed using a NIR laser system. For the pure Cu film, nanoparticles were produced for the accumulated energy (AE) densities in the range of 0.6–11 J/cm². The particle size...

High-entropy alloys (HEAs) have been the focus of wide-ranging studies for their applications as next-generation structural materials. For high-temperature industrial applications, creep behavior of structural materials is critical. In addition to high-temperature tensile, compressive, and notched tests, elevated-temperature nanoindentation is a re...

In this study, the microstructure, hardness, and wear resistance of two kinds of copper alloy are demonstrated to be affected by both composition, annealing temperature, and phases present with a sliding block-on-ring test, where the ring is 316 stainless steel. With a higher content of Zn, the solubility of Mn and Si would decrease, resulting in i...

TiZr-based metallic glass has a unique glass transition point. It is located at the top of the first exothermic peak instead of at the typical endothermic transformation reaction before the supercooled liquid region (∆T x ). It is hard to identify the glass transition temperature (T g ) and ∆T x of these TiZr-based amorphous alloys by an exothermic...

Transparent conducting oxide (TCO) films are widely used throughout the optoelectronics industry. The present study explores the optoelectronic responses of AgZr (AZ) and ITO/AgZr (IAZ) thin film metallic glasses (TFMGs) with different Ag and Zr compositions and processed by two different annealing methods, namely furnace anneal-ing (FA) and laser...

Chemically integrated hybrid nanostructures of Fe 2 O 3 /holey graphene frameworks (Fe 2 O 3 /HGF) nanocomposites have been successfully synthesized via a glycerol activated process. Defected graphene oxides were first etched by a certain volume of hydrogen peroxide. Subsequently, multi-dimensionally nanosized Fe 2 O 3 particles were generated and...

Nanoporous silver (NPS) with an extreme coarsened 3-dimensional bi-continuous ligament and nanopore structure could be prepared by chemical dealloying with high-intensity ultrasonic irradiation (UI). The formation mechanism of NPS dealloying with UI was different from NPS obtained through free corrosion. It evolved into NPS with a new lump forming-...

Fe 41 Cr 15 Co 7 Mo 14 C 12 B 9 Y 2 (Fe-B9) bulk metallic glass (BMG) rods with high glass forming ability and large supercooled liquid (SCL) region were fabricated by arc melting and suction casting. The amorphous state of these Fe-B9 BMG rods was ascertained by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The thermoplastic...

In this study, creep behavior of the face-centered-cubic (FCC) {111} and {100} grains in single-phase Fe20Co20Ni20Cr20Mn20 and dual-phase Fe18Co18Ni20Cr18Mn18Al8 high-entropy alloys (HEAs) was evaluated using a nanoindentation method over temperatures range of 300–600 °C. We measured the creep response of the two different grain orientations in the...

J.C. Huang’s name appeared incorrectly on the original version of this article. It appears correctly here.

The influence of temperature ramping ageing treatment on the microstructure and mechanical properties of Al-Zn-Mg alloy was investigated. When the final temperature was higher than 180°C, the hardness of the alloy improved with increase of the ramping rate. It increased and then decreased with increase of the ramping rate when the final temperature...

The ZrCu-B2 phase can effectively increase the plasticity for some specified Zr based metallic glasses composite (BMGC) by transformation induced plasticity (TRIP) mechanism. However, large and non-uniformly distributed ZrCu-B2 phases usually precipitate in the Zr-based BMGC samples by conventional copper mold casting. Therefore, the concept of ino...

Silks from Nephila pilipes spiders native to Taiwan, obtained from the major ampullate gland, display novel piezoelectric properties that have been exploited in the preparation of energy harvesters. An energy harvester incorporating approximately 100 pieces of spider silk, each approximately 10 mm long, produced a voltage output of 13.4 mV when vib...

A promising Mg-Zn-Y alloy with the long-period stacking ordered (LPSO) second phase has been developed for about twenty years. Because the LPSO phase has the unique 18R crystal structure, particularly for its packing sequence along [0001], as well as it plays an important role in strengthening mechanisms, it is interesting to clarify in terms of me...

Gradient porous materials are gradually developed for some biomedical implants such as mandible and vertebrae to meet the varied Young's modulus due to serious bone density variation and thus to avoid serious stress shielding effect. In this study, different designs of gradient porous materials are fabricated by additive manufacturing 3D printing v...

In this study, an Ag-Cu alloy was chosen as the electrode in conductive bridging random access memory (CBRAM), with results indicating a significant decrease in forming voltage. In addition, resistive switching characteristics as well as a retention test indicated better stability and a resistive switching window of at least an order. The switching...

In order to develop Ti based alloys with promising biocompatibility and matching mechanical response with human bone, TiTaNb alloys with 15, 23 and 30 mass% Ta are designed and systematically examined in terms of microstructural evolution and mechanical response. The Ti-30mass%Ta-10mass%Nb is demonstrated to be satisfactory with an elastic modulus...

In this research, nanoporous silver foams are fabricated through dealloying Ag35Al65 (as atomic percentage, at%) thin films in supercritical (SC) carbon dioxide. The supercritical CO2 is mixed with either HCl, water or H2C2O4 aqueous solution as the solute in the reaction chamber. Due to the low tension of the supercritical fluid, under the best op...

Recently, nanocomposite coatings have been widely used for protective coatings at high temperature owing to the superior mechanical strength over a broad operating temperature. However, there is still room for improvement on lubricating behavior of the coatings. Molybdenum is a promising candidate to further enhance the lubricating properties becau...

Nanoporous silver (NPS) was fabricated by dealloying Ag–Al alloy ribbons with nominal compositions of 30, 35 and 40 at% Ag (corresponding to hypoeutectic composition, eutectic composition and hypereutectic composition, respectively). The microstructures of the Ag–Al precursor and as-dealloyed samples were observed using a scanning electron microsco...

The alloy composition of Zr54Al17Co29 with high glass forming ability (GFA) in the Zr-Al-Co system was predicted by using the multiple binary eutectic clusters from the phase diagram. Then the microalloying effects of Ta on the microstructure, thermal properties, mechanical properties, and corrosion resistance of (Zr54Al17Co29)100-xTax (x = 0, 1, 1...

Most high entropy alloys (HEAs) are cast to form single phase solid solution. Their hardness and strength at room temperature under the as-cast condition are typically lower than expectation. In the research, the ultrasonic surface mechanical attrition treatment (SMAT) is conducted on the surface of two HEAs, FeCoNiCrMn and FeCoNiCrMn-Al, to upgrad...

The open-cell porous Ti-6Al-4V structure with high porosity, intended to be applied as replacement for human cancellous bone, were fabricated by electron beam melting (EBM). Computer aided design (CAD) was applied to design porous structures using the same unit cell with different unit cell sizes from 2.5 to 4 mm, different ligament widths from 600...

In this study, ultrasonic mechanical coating and armoring (UMCA) with subsequent annealing is applied to improve surface hardness of Al. The micro-scaled CuO powders are bombarded and inserted into Al by UMCA, leading to the increment in surface hardness by 6 times. The grain refinement, work hardening and dispersion hardening are contributed to su...

This paper describes the application of piezoelectric fibers and films formed using near-field electrospinning (NFES) and electrospray (ESP) technology. Poly(-methyl L-glutamate) (PMLG), a biocompatible material, was mixed with poly(ethylene oxide) (PEO) and surfactant to obtain a solution of appropriate viscosity and conductance. Because the orien...

With the long-period stacking ordered (LPSO) second phase, the promising mechanical properties of the Mg-Zn-Y alloys have been demonstrated. Because the LPSO phase plays an important role in strengthening mechanisms and it has the unique 18R crystal structure, it is interesting to clarify the deformation mechanism and size effect associated with th...

The Ti/Zr-based metallic glasses (MGs) with various Cu contents are prepared, with nominal compositions of Ti45Zr40Si15 (Cu-free), Ti45Zr40Si10Cu5 (low-Cu), and Ti45Zr20Cu35 (high-Cu). The mechanical properties, corrosion resistance, and in-vitro biocompatibility of these MGs are investigated by means of nano-indentation, electrochemical analyses,...

It has been demonstrated that the Al-Ni-Y based thin film metallic glass composites (TFMGCs) can provide high optical reflectivity, especially over the UV regime, suitable for various optical devices such as optical coating or as functional layer. When such optical devices are applied in humid environment which is sensitive to bacteria or fungus, t...

Tantalum (Ta) is considered as one of the most promising metal due to its high corrosion resistance, excellent biocompatibility and cell adhesion/in-growth capabilities. Although there are some researches exploring the biomedical aspects of Ta and Ta based alloys, systematic characterizations of newly developed Ta-based metallic glasses in bio-impl...

The open-cell porous Ti-6Al-4V structure, intended to be applied as replacement for human cortical and cancellous bone, are fabricated by selective laser melting (SLM). The computer aided design (CAD) was used to design porous structures in various porosity levels from 40% to 80% and with pore sizes from 600 to1000 μm, in order to fit the bone-tiss...

It has been decade-long and enduring efforts to decipher the structural mechanism of plasticity in metallic glasses; however, it still remains a challenge to directly reveal the structural change, if any, that precedes; and dominant plastics flow in them. Here, by using the dynamic atomic force microscope as an “imaging” as well as a “forcing” tool...

Safety and reliability are crucial issues for medical instruments and implants. In the past few decays, bulk metallic glasses (BMGs) have drawn attentions due to their superior mechanical properties, good corrosion resistance, antibacterial and good biocompatibility. However, most Zr-based and Ti-based BMGs contain Ni as an important element which...

In crystalline metals at small scales, the dislocation density will be increased by stochastic events of dislocation network, leading to a universal power law for various material structures. In this work, we develop a model obeyed by a probability distribution of dislocation density to describe the dislocation formation in terms of a chain reactio...

Aluminum alloys, applied as heat sink, are often inherent with high thermal conductivity but poor infrared radiation emissivity. Thus high emissivity coating is often added on the Al substrate in decreasing surface temperature by radiation. In this study, efforts were made in using the ultrasonic mechanical coating and armoring (UMCA) technique to...

Zr-based bulk metallic glass composite (BMGC) presents superior unique properties, including high hardness, high fracture strength, high toughness, large elastic limit, excellent corrosion resistance, and was believed as a promising material for medical-tool applications. In this study, the 4 mm diameter rods of ZrCuAlAgSi-based (Zr-based) BMGC con...

The 3D printed bulk samples fabricated by selective laser melting (SLM) of the additive manufacturing technique are usually considered to be 3D isotropic in microstructures and mechanical responses. This study systematically investigates the anisotropic responses in terms of hardness and electrochemical resistance for the X-, Y- and Z-planes of the...

The mechanical responses of LiAlO2 single crystals on the (001) c-plane and (100) a-plane are examined by using nanoindentation and compression testing, extracting the millimeter-, micrometer-, and nanometer-scaled data. Apparent sample size effects on the yield stress are observed, increasing from 0.5-1 GPa in millimeter scale up to 11-14 GPa in n...

The nanoindentation time-dependent creep experiments with different peak loads are conducted on c-plane (0001), a-plane (110) and m-plane (100) of single-crystal ZnO. Under nano-scaled indentation, the creep behavior is crystalline orientation-dependent. For the creep on (0001), the stress exponent at low loads is ∼1 and at high loads ∼4. The stres...

In this paper, the effects of microstructure on fracture toughness were studied in Al-Cu-Mg alloy, including 2024 and 2124. As the ratio of Cu and Mg was similar in both alloys, the impurity elements in 2024 would lead to the formation of A16(Mn,Fe) and Al7Cu2Fe phases, which could affect the tensile strength and fracture toughness of the alloy. Wi...

The affection of Cu content on the phase evolution of Ag-Cu alloys was investigated by electrochemical noise (EN) with Hilbert spectra analysis. The results showed that the dealloying corrosion rate decreased and contribution of the transient shift from low-frequency parts (diffusion process) to the high-frequency parts (dissolution process) increa...

Rod samples of Mg 60 Zn 35 Ca 5 bulk metallic glass composites (BMGCs) dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA) and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (V f) of Ti particles. The result...

Rod samples of Mg60Zn35Ca5 bulk metallic glass composites (BMGCs) dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA) and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (Vf) of Ti particles. The results show...

A freeform lens with inclined reflector coated with Al-Ni-Y thin film metallic glasses (TFMG) was proposed to improve the irradiance and uniformity of ultraviolet light-emitting diode (UV-LEDs) lithography system. Polydimethylsiloxane (PDMS) was adopted as lens materials. The lens mold was fabricated by 3-D printing method. Besides, a recipe of TFM...

Additive manufacturing (AM) has the advantages of fabricating complex models for application. In this study, cube structure with various porosity is manufactured by AM of selective laser melting (SLM). CAD software is used to create the micro porosity of sample models from 60 %∼80 %. The models are printed by Ti-6Al-4V powders. The morphology of th...

Many multilayered nano-structures appear to fail due to brittle matter along the interfaces. In order to toughen them, in this study, the microstructure and interface strength of multilayered thin films consisting of amorphous ZrCu and nanocrystalline Cu (with sharp or graded interfaces) are examined and analyzed. The interface possesses a gradient...

The mechanical behavior of single crystal Al sample with different sizes in mini-, micro- and nano-scales and different loading directions along [111] and [110] have been systematically investigated. The sample size and orientation effects are examined. The results are compared with previously reported data on other face-centered cubic Ni, Cu, Au a...

Nanoindentation time-dependent relaxation tests were performed on the amorphous ZrCu, nanocrystalline Zr and multilayer ZrCu/Zr thin films aiming to explore the different time-dependent behaviors of these materials under the similar load level at room temperature. There appears an interesting crossing phenomenon of the creep rate as a function of a...