scholarly journals The Microalloying Effect of Ce on the Mechanical Properties of Medium Entropy Bulk Metallic Glass Composites

Crystals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 483
Author(s):  
Yanchun Zhao ◽  
Pengbiao Zhao ◽  
Wensheng Li ◽  
Shengzhong Kou ◽  
Jianlong Jiang ◽  
...  
Keyword(s):  
Fracture Strength ◽  
Work Hardening ◽  
Magnetic Levitation ◽  
Transition Process ◽  
Martensite Phase ◽  
Mixing Enthalpy ◽  
Size Difference ◽  
Face Centered Cubic ◽  
High Fracture ◽  
Thermally Induced

Novel ultra-strong medium entropy bulk metallic glasses composites (BMGCs) Fe65.4−xCexMn14.3Si9.4Cr10C0.9 and Ti40−xCexNi40Cu20 (x = 0, 1.0), through the martensite transformation induced plasticity (TRIP effect) to enhance both the ductility and work-hardening capability, were fabricated using magnetic levitation melting and copper mold suction via high frequency induction heating. Furthermore, the Ce microalloying effects on microstructure and mechanical behaviors were studied. The Fe-based BMGCs consisted of face-centered cubic (fcc) γ-Fe and body-centered cubic (bcc) α-Fe phase, as well as Ti-based BMGCs containing supercooled B2-Ti (Ni, Cu) and a thermally induced martensite phase B19’-Ti (Ni, Cu). As loading, the TRIP BMGCs exhibited work-hardening behavior, a high fracture strength, and large plasticity, which was attributed to the stress-induced transformation of ε-Fe martensite and B19’-Ti (Ni, Cu) martensite. Ce addition further improved the strengthening and toughening effects of TRIP BMGCs. Adding elemental Ce enhanced the mixing entropy ΔSmix and atomic size difference δ, while reducing the mixing enthalpy ΔHmix, thus improving the glass forming ability and delaying the phase transition process, and hence prolonging the work-hardening period before fracturing. The fracture strength σf and plastic stress εp of Ti39CeNi40Cu20 and Fe64.4CeMn14.3Si9.4Cr10C0.9 alloys were up to 2635 MPa and 13.8%, and 2905 MPa and 30.1%, respectively.

scholarly journals Compositional Dependence of Phase Selection in CoCrCu0.1FeMoNi-Based High-Entropy Alloys

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1290 ◽  
Author(s):  
Ning Liu ◽  
Chen Chen ◽  
Isaac Chang ◽  
Pengjie Zhou ◽  
Xiaojing Wang
Keyword(s):  
Molar Ratio ◽  
Mixing Enthalpy ◽  
High Entropy Alloy ◽  
Valence Electron Concentration ◽  
Face Centered Cubic ◽  
Distortion Parameter ◽  
Local Lattice Distortion ◽  
Phase Selection ◽  
High Entropy ◽  
Fcc Structure

To study the effect of alloy composition on phase selection in the CoCrCu0.1FeMoNi high-entropy alloy (HEA), Mo was partially replaced by Co, Cr, Fe, and Ni. The microstructures and phase selection behaviors of the CoCrCu0.1FeMoNi HEA system were investigated. Dendritic, inter-dendritic, and eutectic microstructures were observed in the as-solidified HEAs. A simple face centered cubic (FCC) single-phase solid solution was obtained when the molar ratio of Fe, Co, and Ni was increased to 1.7 at the expense of Mo, indicating that Fe, Co, and Ni stabilized the FCC structure. The FCC structure was favored at the atomic radius ratio δ ≤ 2.8, valence electron concentration (VEC) ≥ 8.27, mixing entropy ΔS ≤ 13.037, local lattice distortion parameter α2 ≤ 0.0051, and ΔS/δ2 > 1.7. Mixed FCC + body centered cubic (BCC) structures occurred for 4.1 ≤ δ ≤ 4.3 and 7.71 ≤ VEC ≤ 7.86; FCC or/and BCC + intermetallic (IM) mixtures were favored at 2.8 ≤ δ ≤ 4.1 or δ > 4.3 and 7.39 < VEC ≤ 8.27. The IM phase is favored at electronegativity differences greater than 0.133. However, ΔS, α2, and ΔS/δ2 were inefficient in identifying the (FCC or/and BCC + IM)/(FCC + BCC) transition. Moreover, the mixing enthalpy cannot predict phase structures in this system.

Comparison of Fracture Strength and Fracture Modes of Zirconia Dental Ceramics Manufactured by Four Different CAD/CAM Systems

2011 ◽  
Vol 492 ◽  
pp. 30-34
Author(s):  
Dan Wang ◽  
Yuan Zhi Xu ◽  
Cheng Lin Lu ◽  
Qi Xiang Yang ◽  
Dong Sheng Zhang ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Critical Load ◽  
Fracture Strength ◽  
Fracture Load ◽  
Image Correlation ◽  
Zirconia Ceramic ◽  
Dental Ceramics ◽  
High Fracture ◽  
Fracture Modes ◽  
Cad Cam

Four sorts of zirconia dental ceramic systems including Cercon smart, Lava, Porcera, and CEREC 3 were studied to analyze fracture mechanism of different CAD/CAM zirconia ceramic. In each system, 12 sectioned specimens were prepared, 6 specimens were taken as controlled group, 6 as experimental group. Quasi-statistic loading before and after cyclic loading was applied at the veneer surface of the specimen. Deformation and crack initiation were monitored with camera in order to carry out digital image correlation (DIC) analysis. The results showed that median cracks were observed under the yielding zone. Specimens fractured along the core/veneer interface with the crack growth. No cone crack was confirmed and fracture only existed in veneer layer. After cyclic loading there were no significant differences for the four ceramic systems in terms of the critical load, while significant differences existed in terms of the fracture load. Both critical load and fracture load were lowered after cyclic loading. After cycling loading, the 4 tested zirconia CAD/CAM ceramic possess high fracture strength to meet the requirement for oral functions. The fracture modes of the four zirconia ceramic systems indicate that the strength of the veneer should be enhanced.

Enhanced Mechanism of Fracture Toughness in Cannon Bone

2008 ◽  
Vol 368-372 ◽  
pp. 1651-1653
Author(s):  
Bin Chen ◽  
X. Peng ◽  
S. Sun
Keyword(s):  
Fracture Toughness ◽  
Fracture Strength ◽  
Biological Material ◽  
Collagen Matrix ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Sem Observation ◽  
Representative Model ◽  
Parallel Distribution

As a typical biological material, bone possesses high fracture strength and fracture toughness, which are closely related to its exquisite microstructure. SEM observation of a cannon bone shows that the bone is a kind of layered bioceramic composite consisting of hydroxyapatite sheets and collagen matrix. The hydroxyapatite sheets are of long and thin shape, distributing in parallel. The fracture toughness of the bone is analyzed with the representative model of the hydroxyapatite sheets and the concept of maximum pullout energy. It is shown that the lathy shape as well as the parallel distribution of the hydroxyapatite sheets increases the pullout energy and endows the bone with high fracture toughness.

Monte Carlo Simulation of Phase Separation Behavior in a Cu-Co Alloy Nanoparticle

2002 ◽  
Vol 17 (5) ◽  
pp. 925-928 ◽  
Author(s):  
Jae-Hyeok Shim ◽  
Byeong-Joo Lee ◽  
Jae-Pyoung Ahn ◽  
Young Whan Cho ◽  
Jong-Ku Park
Keyword(s):  
Monte Carlo ◽  
Phase Separation ◽  
Alloy System ◽  
Mixing Enthalpy ◽  
Interatomic Potentials ◽  
Face Centered Cubic ◽  
Embedded Atom ◽  
Mc Simulation ◽  
Phase Separation Behavior ◽  
Separation Behavior

The phase separation behavior in a Cu–Co nanoparticle was investigated using Monte Carlo (MC) simulation. The modified embedded atom method (MEAM) was adopted to describe the interatomic potentials for the Cu–Co alloy system. Some of the cross potential parameters were fitted with experimental data such as mixing enthalpy and lattice constants of Cu–Co alloys. The present MC simulation combined with the MEAM potential describes well the phase separation between face-centered-cubic (fcc) Cu and fcc Co during the annealing of the particle.

scholarly journals Microstructures of ZrO2-Al2O3 Composites with High Fracture Strength.

1992 ◽  
Vol 39 (2) ◽  
pp. 92-97
Author(s):  
Ryoichi Shikata ◽  
Taiji Yamamoto ◽  
Takeshi Shiono ◽  
Tomozo Nishikawa
Keyword(s):  
Fracture Strength ◽  
High Fracture

scholarly journals Atomistic Study on Size Effects in Thermally Induced Martensitic Phase Transformation of NiTi

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Sourav Gur ◽  
George N. Frantziskonis
Keyword(s):  
Thin Films ◽  
Phase Transformation ◽  
Size Effects ◽  
Martensite Phase ◽  
Martensitic Phase ◽  
Martensitic Phase Transformation ◽  
Phase Fraction ◽  
Interatomic Potentials ◽  
Thermally Induced ◽  
Atomistic Study

The atomistic study shows strong size effects in thermally induced martensitic phase transformation evolution kinetics of equiatomic NiTi shape memory alloys (SMAs). It is shown that size effects are closely related to the presence of free surfaces; thus, NiTi thin films and nanopillars are studied. Quasi-static molecular dynamics simulations for several cell sizes at various (constant) temperatures are performed by employing well-established interatomic potentials for NiTi. The study shows that size plays a crucial role in the evolution of martensite phase fraction and, importantly, can significantly change the phase transformation temperatures, which can be used for the design of NiTi based sensors, actuators, or devices at nano- to microscales. Interestingly, it is found that, at the nanometer scale, Richard’s equation describes very well the martensite phase fraction evolution in NiTi thin films and nanopillars as a function of temperature.

Selective laser melting of nano-TiB 2 decorated AlSi10Mg alloy with high fracture strength and ductility

2017 ◽  
Vol 129 ◽  
pp. 183-193 ◽  
Author(s):  
X.P. Li ◽  
G. Ji ◽  
Z. Chen ◽  
A. Addad ◽  
Y. Wu ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Fracture Strength ◽  
Laser Melting ◽  
High Fracture ◽  
Strength And Ductility
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