Daolun Chen

Daolun Chen
Ryerson University · Department of Mechanical Engineering

Dr.rer.nat., Ph.D.

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345
Publications
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11,483
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Publications

Publications (345)
Article
The aim of this study was to determine cyclic deformation behavior of a high-pressure die-cast Silafont®-36 automotive alloy with heterogeneous microstructures, focusing on the effect of strain ratio (Rε) ranging from negative infinity (-∞) to +0.5 at a constant strain amplitude of 0.4%. Pronounced cyclic hardening behavior was observed from the st...
Article
Full-text available
3D printing (or more formally called additive manufacturing) has the potential to revolutionize the way objects are manufactured, ranging from critical applications such as aerospace components to medical devices, making the materials stronger, lighter and more durable than those manufactured via conventional methods. While the mechanical propertie...
Article
Heterogeneous materials are regarded as an emerging class of structural materials with superior balanced performance relative to the conventional unimodal counterparts. In the present study, the cyclic deformation behavior of carbon nanotube (CNT)-reinforced 2009Al nanocomposite with a bimodal-grain structure was studied via strain-controlled fatig...
Article
The aim of this study was to identify cyclic deformation behavior of a high-pressure die-cast Silafont®-36 automotive cast aluminum alloy consisting of heterogeneous composite-like microstructures of nearly circular eutectic silicon particles embedded in Al matrix, with particular attention to fatigue life prediction. The alloy exhibited superior f...
Article
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The aim of this study was to characterize detailed microstructural changes and bonding characteristics and identify the formation mechanism of collision surface of Al6061–Q355 steel dissimilar welded joints via electromagnetic pulse welding (EMPW). The collision surface was observed to consist of five zones from the center to the outside. The centr...
Article
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The purpose of this study is to identify the high-temperature oxidation mechanisms of a Ti2AlNb-based alloy via detailed analyses of oxide scale/substrate interface using transmission electron microscopy, X-ray diffraction and thermodynamic calculations. Oxygen is first adsorbed on the alloy surface, reacting with B2 phase to generate TiO2. The dep...
Article
Silicon nitride (Si3N4) ceramics with Al2O3, MgO and Y2O3 as sintering additives were fabricated via hot-pressing sintering and gas pressure sintering, respectively, focusing on the texture and fracture toughness. The hardness and fracture toughness on the plane perpendicular and parallel to the hot-pressing direction were different in the hot-pres...
Article
The aim of this study was to identify deformation behavior and strengthening mechanisms of a carbon nanotube (CNT)-reinforced bimodal-grained Al-Cu-Mg nanocomposite and its base alloy fabricated by two-step ball milling, powder metallurgy and extrusion. A superior strength-ductility synergy stemming from the concurrent presence of ultrafine grains...
Article
Aluminum alloy is today considered as a prime selection for manufacturing lightweight structural components in the automotive industry to increase fuel efficiency and reduce harmful emissions. The aim of this study was to identify the effect of microstructure and strain rate on the tensile deformation behavior of a high-pressure die-cast Silafont®-...
Article
Coiled tubing (CT) steel is widely used in the oil and gas industry. It is worth noting that CT steels of different grades show similar microstructures but their mechanical and tribological properties can be quite different. The underlying mechanism is unclear, making it difficult to further tailor the CT steel with clear guidelines for specific ap...
Article
The purpose of this study was to examine weldability of an AA7072-cladded high-strength AA7075-T6 via ultrasonic spot welding, focusing on the influence of welding energy on mechanical properties and failure mechanisms. Defect-free sound joints were achieved with robust bonding and grain refinement via dynamic recrystallization at the weld interfac...
Article
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Additive manufacturing (AM) is a promising material processing method which gains significant momentum in the aerospace and biomedical industries. However, the anisotropy in the mechanical properties of additively-manufactured materials is still poorly understood. This study was aimed at elucidating crystallographic feature-anisotropy-mechanical pr...
Article
Due to its corrosion resistance, modifiable mechanical properties, and electrical conductivity, etc., CuNi alloy has found a wide variety of industrial applications, especially in the marine environment. It is highly desired if the mechanical strength and wear resistance of CuNi alloy can reach a level comparable to that of steel while keeps its co...
Article
The aim of this study was to characterize detailed interfacial microstructures and evaluate tensile properties of Al6061-to-Cu dissimilar welded joints via electromagnetic pulse welding (EMPW) at different discharge voltages. The EMPWed joints consisted of annular weld zone and central non-weld zone. The outer and inner regions of annular weld zone...
Article
The main purpose of this investigation was to identify microstructure and cyclic deformation behavior of a 3D-printed Ti–6Al–4V alloy via selective electron beam melting (SEBM). Abundant orientated α-lamellae were present in the prior columnar β grains along the building direction. Four distinct high-angle α/α grain boundaries were detected as stip...
Chapter
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Additive manufacturing or 3D-printing of titanium alloys with a high strength-to-weight ratio holds significant interest in the aerospace and biomedical industries. The purpose of this investigation was to determine microstructure and tensile deformation behavior of a 3D-printed Ti-6Al-4V alloy via selective electron beam melting (SEBM). Plentiful...
Article
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Ti2AlNb-based intermetallic compounds are considered as a new category of promising lightweight aerospace materials due to their balanced mechanical properties. The aim of this study was to evaluate monotonic and cyclic deformation behavior of an as-cast Ti-22A1-20Nb-2V-1Mo-0.25Si (at.%) intermetallic compound in relation to its microstructure. The...
Article
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Lightweight ZEK100-O Mg alloy and Al6022-T43 Al alloy with an Ag interlayer were joined via ultrasonic spot welding (USW), focusing on the microstructural change and tensile lap shear strength of the welded joints in relation to welding energy. Mg/Al interface was superseded by Mg/Ag and Al/Ag interfaces, and unfavorable Mg17Al12 intermetallic comp...
Article
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Aluminum composites reinforced with ceramic whiskers exhibited a unique combination of high specific strength and superior specific modulus. A 20 vol.% Si3N4w/Al-11.5Si-1.0Mg-0.5Cu-0.5Ni (wt.%) composite was fabricated via squeeze casting in the present study. It was observed that the addition of silicon nitride (Si3N4) whiskers in the Al-Si cast a...
Article
The present review encapsulates the investigations carried out in the area of aluminum (Al) matrix composites reinforced with carbon nanotubes (CNTs). The application of CNT reinforcement in aluminum alloys is driven by its exceptional chemical and mechanical properties. The critical issues in the processing techniques, challenges in the interfacia...
Article
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The aim of this study was to identify and analyze the fatigue fracture characteristics of dissimilar Al 6061 to Cu (UNS C11000) lap joints made with ultrafast electromagnetic pulse welding (EMPW) via fractography, stress analysis and finite element simulation. It was observed that EMPW generated an annular (or ring-shaped) bonding area, with weld z...
Preprint
Full-text available
A new mechanism of dynamic phase transformations of α 2 ↔ γ in an isothermally forged γ-TiAl-based alloy that occur simultaneously during a short-term exposure at 1000 • C is identified in this study. In the heating process, γ phase significantly decreases through a phase transformation of γ → α 2 , while new γ lamellae are precipitated in the inte...
Article
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Commercially-pure (CP) titanium was first processed via cryogenic deformation to activate high-density deformation twins, and was subsequently annealed at 500°C to induce static recrystallization (SRX). Two types of twins were mainly activated during cryogenic deformation, i.e. , { 11 2 ¯ 2 } contraction twins and { 10 1 ¯ 2 } extension twins. Mult...
Article
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The mechanical response of a servo-hydraulic testing system is affected by the stiffness of test specimens. An adaptive controller helps in auto-tuning the system by setting the optimal proportional-integral-derivative values for the subsequent test as the stiffness changes. This paper presents the effect of auto-tuning of various channels on the f...
Article
Full-text available
and some remaining γ-TiAl phases were observed to be co-existent. The first-principles calculations of density-functional type based on the generalized-gradient approximation revealed that the metastable κ-Al 2 O 3 can be converted into the stable α-Al 2 O 3. TiN and Ti 2 AlN could be converted into each other to form κ-Al 2 O 3 under specific cond...
Article
The drive for increasing fuel efficiency and decreasing anthropogenic greenhouse effect via lightweighting leads to the development of several new Al alloys. The effect of Mn and Fe addition on the microstructure of Al‐Mg‐Si alloy in as‐cast condition was investigated. The mechanical properties including strain‐controlled low‐cycle fatigue characte...
Article
Dissimilar welding of 2024Al alloy to SiC/2009Al composite was conducted via solid-state ultrasonic spot welding technique. Defect-free sound spot welds were successfully achieved. SiCp particles were observed to migrate from the composite side to 2024Al side along with the interfacial interlocking during the intense high-frequency rubbing, which i...
Article
Full-text available
The high-temperature structural applications of Ti2AlNb-based alloys, such as in jet engines and gas turbines, inevitably require oxidation resistance. The objective of this study is to seek fundamental insight into the oxidation behavior of a Ti2AlNb-based alloy via detailed microstructural characterization of oxide scale and scale/substrate inter...
Article
Full-text available
A pre-cold-deformation process was applied for commercially pure titanium at cryogenic temperature to activate high-density deformation twins, and subsequent hot-deformation was used to induce dynamic recrystallization (DRX). Three major types of twins were effectively activated during cryogenic deformation, including {112¯2} contraction twins, {11...
Article
Full-text available
Lightweight structural applications of magnesium and aluminum alloys inevitably necessitate welding and joining, especially dissimilar welding between these alloys. The objective of this study was to examine the feasibility of joining ZEK100 Mg alloy to Al6022 alloy via ultrasonic spot welding, focusing on effects of welding energy. An interface di...
Article
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In the nuclear industry, there are a number of applications where the transition of stainless steel to Zircaloy is of technological importance. However, due to the differences in their properties there are considerable challenges associated with developing a joining process that will sufficiently limit the heat input and welding time—so as to minim...
Article
Full-text available
Oxidation resistance of titanium aluminide (TiAl) based alloys is a fundamental aspect for the high-temperature structural applications such as in the advanced hypersonic aircraft engines and gas turbines. The aim of this study was to identify oxidation kinetics and mechanisms through detailed microstructural characterization of a newly-developed T...
Chapter
Micro-additions of the transition metals Ti, Zr and V were explored to improve thermal stability of the cast hypoeutectic Al‒7Si‒1Cu‒0.5Mg (wt%) alloy. During high temperature exposures, the Cu- and Mg-rich phases along with the eutectic Si dissolved in the temperature range from 300 to 500 °C whereas the (AlSi)x(TiVZr) phases, containing transitio...
Article
Twinning and detwinning represent major deformation mechanisms in hexagonal close-packed (hcp) metals. The aim of this study was to identify twin-twin interactions and contraction twin formation in an AZ31 magnesium alloy when the compressive direction was changed from the extrusion direction (ED) to the normal direction (ND) via electron backscatt...
Article
This study was aimed at identifying underlying strengthening mechanisms and predicting the yield strength of as-extruded Mg-Zn-Y alloys with varying amounts of yttrium (Y) element. The addition of Y resulted in the formation of ternary I (Mg3YZn6), W (Mg3Y2Zn3) and LPSO (Mg12YZn) phases which subsequently reinforced alloys ZM31 + 0.3Y, ZM31 + 3.2Y...
Conference Paper
The presented work was aimed at identifying the microstructural features, predominant texture components, hot compression behavior, and processing maps of a CNT-reinforced aluminum matrix composite. The microstructure and main texture components were evaluated via electron backscatter diffraction (EBSD) analysis and the micro-texture results reveal...
Article
The determination of the optimum processing window of a material at elevated temperatures is essential for metal forming. Such an “ideal” processing window could be characterized by the workability parameters of power dissipation efficiency, Ziegler's instability criteria, and the presence of favorable microstructures. The purpose of the present st...
Article
Full-text available
Oxidation resistance is one of key properties of titanium aluminide (TiAl) based alloys for high-temperature applications such as in advanced aero-engines and gas turbines. A new TiAlNbCr alloy with micro-addition of yttrium has been developed, but its oxidation behavior is unknown. To provide some fundamental insights, high-temperature oxidation c...
Article
The aim of this study was to analyze the microstructural changes of two dissimilar Ti-6Al-4V/Ti17 and Ti-6Al-4V/BT9 joints welded via electron beam welding (EBW), and establish the relationship between microstructure and properties. The results showed that the occurrence of phase transformation was mainly dependent on the peak heating temperature d...
Article
The purpose of this study was to identify plastic flow behavior and microstructural evolution during sub-transus hot deformation of a Ti-6Al-4V alloy with three initial microstructures (namely, transformed β microstructure, bimodal microstructure, and α′ martensitic microstructure) through compressive deformation at different strain rates in a Glee...
Article
The influence of nano-precipitates and dislocations on the static and dynamic recrystallization of the Al-Si based alloy modified with additions of Ti-V-Zr and deformed at 400 C followed by annealing at 500 C were studied by using electron backscatter diffraction and transmission electron microscopy. The den-dritic morphology of the undeformed samp...
Article
The microstructure evolution, tensile lap shear strength and fatigue properties of dissimilar ultrasonic spot welded (USWed) joints of aluminum to two commercial steel sheets at different welding energies were investigated. The main intermetallics at the weld interface were θ (FeAl3) in both joints along with eutectic Al-Zn in Al-to-galvanized high...
Article
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The present study focused on single and multiple dissimilar joints between DP980 and high-strength low-alloy (HSLA) galvanized steels. The tensile properties of the dissimilar joint between the strong DP980 and the relatively soft HSLA reflected only the properties of HSLA with plastic deformation, and final fracture took place entirely in HSLA. Th...
Article
Artificial ageing characteristics and high temperature tensile properties of the Al-7Si-1Cu-0.5Mg (wt.%) alloy modified with micro-additions of Mo and Mn, were examined. The modified alloy formed microstructure containing Cu- and Mg-rich phases along with Mo- and Mn-rich dispersoids of complex morphology. During artificial ageing, the alloy reached...
Conference Paper
Full-text available
The use of Advanced High-Strength Steels (AHSS) in automobiles has steadily increased in recent years. In particular, the dual-phase (DP) steels with a desirable combination of strength and ductility are used essentially in every vehicle model, including the "all aluminum" Ford F-150 truck. The fatigue property of fiber laser welds between two DP98...
Article
Multi-material design of automotive structures for lightweighting solutions inevitably involves dissimilar joining of lightweight aluminum alloys with steels. Solid-state ultrasonic spot welding (USW) has recently received significant attention due to its high energy efficiency in comparison with conventional fusion welding techniques. In this stud...
Article
The welded joints are often subjected to cyclic stresses and high-strain-rate deformation resulting in worrisome fatigue failure. Therefore, it is necessary to evaluate the fatigue resistance and cyclic deformation characteristics of these weldments. Ti–6Al–4V–0.3Fe–0.1C–0.05N–0.015H–0.2O (TC4) titanium alloy joints were produced via linear frictio...
Article
Texture evolution and deformation activity of an extruded Mg-Zn-Mn (ZM31) alloy containing different amounts of yttrium subjected to hot compression along the extrusion direction at 200 °C and 300 °C were studied via electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). A typical basal texture with (0001) planes and 〈011¯0〉 direction...
Article
The aim of this study was to examine the feasibility of joining a low rare-earth containing ZEK100 Mg alloy to 5754 Al alloy via solid-state ultrasonic spot welding (USW), and evaluate the interface microstructure, tensile lap shear strength, and fatigue life. A diffusion layer consisting of eutectic structure of α-Mg and Al12Mg17 intermetallic com...
Article
The high reactivity of magnesium limits its extensive applications in the transportation industry for the development of lightweight vehicles and aircrafts. In addition to modification of the corrosion potential of bulk magnesium through alloying elements, tailoring its surface oxide film is an alternative approach for enhanced resistance corrosion...
Article
Two dissimilar ultrasonic spot welded joints of aluminum to commercial steel sheets at different levels of welding energy were investigated. The tensile lap shear tests were conducted to evaluate the failure strength in relation to microstructural changes. The main intermetallics at the weld interface in both joints was θ (FeAl3), along with ɳ (Fe2...
Article
The present study was aimed to evaluate the strain-controlled cyclic deformation characteristics and low cycle fatigue (LCF) life of a low (~0.3 wt.%) Ce-containing ME20-H112 magnesium alloy. The alloy contained equiaxed grains with ellipsoidal particles containing Mg and Ce (Mg12Ce), and exhibited a relatively weak basal texture. Unlike the high r...
Article
The present study was aimed to evaluate the strain-controlled cyclic deformation characteristics and low cycle fatigue (LCF) life of a low (~0.3 wt%) Ce-containing ME20-H112 magnesium alloy. The alloy contained equiaxed grains with ellipsoidal particles containing Mg and Ce (Mg12Ce), and exhibited a relatively weak basal texture. Unlike the high ra...
Article
Full-text available
The hypoeutectic Al-7Si-1Cu-0.5Mg base alloy was modified with different contents of Zr, V and Ti. The wedge-shape samples with varying solidification rates during casting were subjected to isochronal aging at temperatures up to 500 °C. Moreover, as-cast and solution treated alloys were subjected to long-term isothermal aging at 150°C. As a referen...
Article
Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeM...
Conference Paper
Lightweight magnesium (Mg) alloys are increasingly used in the transportation industries to reduce the weight of vehicles due to their high strength-to-weight ratio. The applications of Mg alloys inevitably involve welding and joining. Ultrasonic spot welding (USW), an emerging and promising solid-state joining technology, can be suitably applied t...
Book
In recent years Mg-Zn-Y series alloys have drawn significant interest due to their superior mechanical properties. The addition of yttrium to the Mg-Zn alloy leads to the formation of a special phase (Mg12YZn) with a long-period stacking ordered (LPSO) structure, which plays an important strengthening role. The main objective of this study was to i...
Article
Tensile and low cyclic fatigue tests were used to assess the influence of micro–additions of Ti/V/Zr on the performance of Al–7Si–1Cu–0.5Mg (wt.%) alloys in the as–cast and T6 heat-treated conditions and their improvement was compared to the base alloy. The microstructure of the as–cast Al–7Si–1Cu–0.5Mg (wt.%) base and modified alloys consisted of...
Article
Ultrasonic spot welding was used to join a low rare-earth containing ZEK100 Mg alloy at different levels of welding energy, and tensile lap shear tests were conducted to evaluate the failure strength in relation to the microstructural changes. It was observed that dynamic recrystallization occurred in the nugget zone; the grain size increased and m...
Article
The purpose of this investigation was to evaluate the microstructural change, lap shear tensile load, and fatigue resistance of ultrasonic spot welded joints of aluminum 5754 alloy for automotive applications. A unique “necklace”-type structure with very fine equiaxed grains was observed to form along the weld line due to the mechanical interlockin...
Article
Tensile and low cyclic fatigue properties were used to assess the influence of Mn additions and heat treatment on the performance of the Al-7Si-1Cu-0.5 Mg (wt.%) alloy. As a reference, the Mn-free base and the currently used automotive alloys A380 and A319 were used. In the as-cast state, the Mn-modified alloy comprised of the α-Al, eutectic Si, an...
Article
Due to excellent chemical stability, high rigidity, superior corrosion and wear resistance, aluminum oxynitride (AlON) has been considered as one of most promising candidate ceramic materials in high-performance structural, advanced abrasives and refractory fields. However, it usually exhibited relatively low flexural strength and poor fracture tou...