scholarly journals Discovery of New Ti-Based Alloys Aimed at Avoiding/Minimizing Formation of α” and ω-Phase Using CALPHAD and Artificial Intelligence

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Rajesh Jha ◽  
George S. Dulikravich
Keyword(s):  
Artificial Intelligence ◽  
Toxic Elements ◽  
Alloy Composition ◽  
Calphad Approach ◽  
Self Organizing Maps ◽  
Β Phase ◽  
Ω Phase ◽  
Complete Dataset ◽  
The Stability ◽  
Python Programming

In this work, we studied a Ti-Nb-Zr-Sn system for exploring novel composition and temperatures that will be helpful in maximizing the stability of β phase while minimizing the formation of α” and ω-phase. The Ti-Nb-Zr-Sn system is free of toxic elements. This system was studied under the framework of CALculation of PHAse Diagram (CALPHAD) approach for determining the stability of various phases. These data were analyzed through artificial intelligence (AI) algorithms. Deep learning artificial neural network (DLANN) models were developed for various phases as a function of alloy composition and temperature. Software was written in Python programming language and DLANN models were developed utilizing TensorFlow/Keras libraries. DLANN models were used to predict various phases for new compositions and temperatures and provided a more complete dataset. This dataset was further analyzed through the concept of self-organizing maps (SOM) for determining correlations between phase stability of various phases, chemical composition, and temperature. Through this study, we determined candidate alloy compositions and temperatures that will be helpful in avoiding/minimizing formation of α” and ω-phase in a Ti-Zr-Nb-Sn system. This approach can be utilized in other systems such as ω-free shape memory alloys. DLANN models can even be used on a common Android mobile phone.

Effect of Oxygen Content on Microstructure and Mechanical Properties of Ti-Nb-Ge Alloys for Biomedical Application

2008 ◽  
Vol 47-50 ◽  
pp. 1450-1453 ◽  
Author(s):  
Won Yong Kim ◽  
Han Sol Kim
Keyword(s):  
Mechanical Properties ◽  
Oxygen Content ◽  
Volume Fraction ◽  
Biomedical Application ◽  
Casting Process ◽  
Alloy System ◽  
Β Phase ◽  
Ω Phase ◽  
Α Phase ◽  
The Stability

The effect of Ge and oxygen content on microstructural formation and mechanical properties of Ti-Nb alloys were investigated in order to design a desirable Ti based alloy through casting process. Three phase mixtures consisting of bcc-structured β phase, orthorhombic structured α" phase and intermediate ω phase were found depending on Nb, Ge, oxygen content in the present alloy system. The volume fraction of α" phase and ω phase decreased with increasing Ge or oxygen content. This microstructural information may indicate that both Ge and oxygen act to increase the stability of β phase rather than α" phase in metastable β-Ti based alloys prepared by water quenching. Elastic modulus values were sensitive to phase stability of constituent phases.

Effect of Nb on the Properties of Ti-Nb Random Alloys from First-Principles

2013 ◽  
Vol 747-748 ◽  
pp. 890-898 ◽  
Author(s):  
Min Jie Lai ◽  
Xiang Yi Xue ◽  
Cai Si Meng ◽  
Hong Chao Kou ◽  
Bin Tang ◽  
...  
Keyword(s):  
First Principles ◽  
Lattice Parameters ◽  
Potential Approximation ◽  
Β Phase ◽  
Ω Phase ◽  
Opposite Situation ◽  
Random Alloys ◽  
The Stability ◽  
Increasing Temperature ◽  
Nb Addition

The effect of Nb on the equilibrium lattice parameters and relative stability between β and ω phases of Ti1-xNbx (0 < x 0.4) random alloys as well as their mechanical properties in body-centered-cubic crystallographic phase was investigated using the exact muffin-tin orbitals method in combination with the coherent potential approximation. It has been found that the calculated lattice parameters of the β phase agree well with the experimental data. For ω phase, the value of a increases almost linearly with increasing Nb concentration, while the opposite situation presented for c/a. Both Nb addition and increasing temperature enhanced the stability of β phase relative to ω phase. The critical Nb concentration for the complete stabilization of β phase at 300 K, 673 K and 1273 K was 22 at.%, 17 at.% and 9 at.%, respectively. The polycrystalline bulk modulus B, Youngs modulus E and shear modulus G increased monotonously with Nb addition and reducing the Nb concentration below 30 at.% resulted in lower E compared to that of Ti-6Al-4V. The calculated G/B values demonstrate that the bcc Ti1-xNbx (0 < x 0.4) random alloys should be intrinsically ductile.

Development of the Snoek Anelastic Relaxation Correlated with Oxygen in β-Ti Alloys

2019 ◽  
Vol 298 ◽  
pp. 59-63 ◽  
Author(s):  
Zheng Cun Zhou ◽  
J. Du ◽  
S.Y. Gu ◽  
Y.J. Yan
Keyword(s):  
Internal Friction ◽  
Physical And Mechanical Properties ◽  
Peak Height ◽  
Relaxation Peak ◽  
Interstitial Oxygen ◽  
Internal Friction Peak ◽  
Β Phase ◽  
Ti Alloys ◽  
Interstitial Atoms ◽  
The Stability

The β-Ti alloys exhibit excellent shape memory effect and superelastic properties. The interstitial atoms in the alloys have important effect on their physical and mechanical properties. For the interstitial atoms, the internal friction technique can be used to detect their distributions and status in the alloys. The anelastic relaxation in β-Ti alloys is discussed in this paper. β-Ti alloys possesses bcc (body center body) structure. The oxygen (O) atoms in in the alloys is difficult to be removed. The O atoms located at the octahedral sites in the alloys will produce relaxation under cycle stress. In addition, the interaction between the interstitial atoms and substitute atoms, e.g., Nb-O,Ti-O can also produce relaxation. Therefore, the observed relaxational internal friction peak during the measuring of internal friction is widened. The widened multiple relaxation peak can be revolved into Debye,s elemental peaks in Ti-based alloys. The relaxation peak is associated with oxygen movements in lattices under the application of cycle stress and the interactions of oxygen-substitute atoms in metastable β phase (βM) phase for the water-cooled specimens and in the stable β (βS) phase for the as-sintered specimens. The damping peak height is not only associated with the interstitial oxygen, but also the stability and number of βM in the alloys.

scholarly journals First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Salloom ◽  
S. A. Mantri ◽  
R. Banerjee ◽  
S. G. Srinivasan
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
First Principles ◽  
Young's Modulus ◽  
Group Vi ◽  
Group V ◽  
Β Phase ◽  
Ti Alloys ◽  
Ω Phase ◽  
Stabilizer Concentration

AbstractFor decades the poor mechanical properties of Ti alloys were attributed to the intrinsic brittleness of the hexagonal ω-phase that has fewer than 5-independent slip systems. We contradict this conventional wisdom by coupling first-principles and cluster expansion calculations with experiments. We show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Studies with five prototypical β-stabilizer solutes (Nb, Ta, V, Mo, and W) show that increasing β-stabilizer concentration destabilizes the ω-phase, in agreement with experiments. The Young’s modulus of ω-phase also decreased at larger concentration of β-stabilizers. Within the region of ω-phase stability, addition of Nb, Ta, and V (Group-V elements) decreased Young’s modulus more steeply compared to Mo and W (Group-VI elements) additions. The higher values of Young’s modulus of Ti–W and Ti–Mo binaries is related to the stronger stabilization of ω-phase due to the higher number of valence electrons. Density of states (DOS) calculations also revealed a stronger covalent bonding in the ω-phase compared to a metallic bonding in β-phase, and indicate that alloying is a promising route to enhance the ω-phase’s ductility. Overall, the mechanical properties of ω-phase predicted by our calculations agree well with the available experiments. Importantly, our study reveals that ω precipitates are not intrinsically embrittling and detrimental, and that we can create Ti-alloys with both good ductility and strength by tailoring ω precipitates' composition instead of completely eliminating them.

Microstructures and Properties of Ti-Nb Alloys Produced by Powder Metallurgy

2011 ◽  
Vol 80-81 ◽  
pp. 431-435 ◽  
Author(s):  
Zheng Cun Zhou ◽  
J. Du ◽  
H. Yang ◽  
S.Y. Gu ◽  
Y.J. Yan
Keyword(s):  
Powder Metallurgy ◽  
Testing Machine ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Sintered Alloy ◽  
Xrd Diffraction ◽  
Β Phase ◽  
Ω Phase ◽  
Nb Content ◽  
And Storage

Ti-Nb alloys were prepared by powder metallurgy. Their microstructures are detected by the XRD diffraction and are observed using an optical microscope. The mechanical properties are tested using a dynamic mechanical analysis (DMA) Q800 from TA Instruments in single cantilever mode and using a 100 KN MTS testing machine with control software. It has been found that the sintered Ti-Nb alloys possess the stable α and β phases and the amount in β phase increases with increasing Nb content. The water quenched Ti-35.4Nb alloy contains α,,and βM. The as-sintered alloy has higher yield stress and storage modulus than the water quenched Ti-35.4Nb alloy, which is resulted from the α phase with high modulus in the as-sintered alloy. The ω phase can be precipitated from βMwhen the water quenched Ti-35.4Nb alloy is aged at 300 °C, causing the modulus to increase since ω phase has large modulus.

Effects of Cooling Rate and Sn Addition on the Microstructure of Ti-Nb-Sn Alloys

2011 ◽  
Vol 172-174 ◽  
pp. 190-195 ◽  
Author(s):  
Giorgia T. Aleixo ◽  
Eder S.N. Lopes ◽  
Rodrigo Contieri ◽  
Alessandra Cremasco ◽  
Conrado Ramos Moreira Afonso ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Melting Furnace ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Β Phase ◽  
Arc Melting ◽  
Ti Alloys ◽  
Ω Phase

Ti-based alloys present unique properties and hence, are employed in several industrial segments. Among Ti alloys, β type alloys form one of the most versatile classes of materials in relation to processing, microstructure and mechanical properties. It is well known that heat treatment of Ti alloys plays an important role in determining their microstructure and mechanical behavior. The aim of this work is to analyze microstructure and phases formed during cooling of β Ti-Nb-Sn alloy through different cooling rates. Initially, samples of Ti-Nb-Sn system were prepared through arc melting furnace. After, they were subjected to continuous cooling experiments to evaluate conditions for obtaining metastable phases. Microstructure analysis, differential scanning calorimetry and X-ray diffraction were performed in order to evaluate phase transformations. Depending on the cooling rate and composition, α” martensite, ω phase and β phase were obtained. Elastic modulus has been found to decrease as the amount of Sn was increased.

Surface Effect in a Metastable β Ti-Nb-Sn Alloy

2021 ◽  
Vol 1035 ◽  
pp. 562-567
Author(s):  
Li Chun Qi ◽  
Wen Xiao Qu ◽  
Yong Qi Zhu ◽  
Qing Liu
Keyword(s):  
Titanium Alloys ◽  
Orientation Relationship ◽  
Surface Effect ◽  
Phase Region ◽  
Martensite Phase ◽  
The Other ◽  
Β Phase ◽  
Ω Phase

The phase compositions of surface and interior in Ti-32Nb-4Sn metastable b alloy were investigated. It was found that this alloy exhibits surface effect significantly different from the effects reported in Ti-10V-2Fe-3Al, Ti-22Nb-9Zr and the other titanium alloys. The surface of Ti-32Nb-4Sn specimen quenched from single b phase region was characterized by dominant b phase and a few of α″ and ω phase. While in the interior of the alloy, a large amount of α² martensite phase was observed in addition to b phase The orientation relationship between the α″ martensite and β phase is (110)β∥(002)α″, (020)β∥(022)α″ and [001]β∥[100]α″.

scholarly journals An Intelligent Multi-View Active Learning Method Based on a Double-Branch Network

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 901
Author(s):  
Fucong Liu ◽  
Tongzhou Zhang ◽  
Caixia Zheng ◽  
Yuanyuan Cheng ◽  
Xiaoli Liu ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Deep Learning ◽  
Active Learning ◽  
Sample Selection ◽  
Training Dataset ◽  
Learning Method ◽  
Active Learning Method ◽  
Level Information ◽  
The Stability ◽  
Different Characteristics

Artificial intelligence is one of the most popular topics in computer science. Convolutional neural network (CNN), which is an important artificial intelligence deep learning model, has been widely used in many fields. However, training a CNN requires a large amount of labeled data to achieve a good performance but labeling data is a time-consuming and laborious work. Since active learning can effectively reduce the labeling effort, we propose a new intelligent active learning method for deep learning, which is called multi-view active learning based on double-branch network (MALDB). Different from most existing active learning methods, our proposed MALDB first integrates two Bayesian convolutional neural networks (BCNNs) with different structures as two branches of a classifier to learn the effective features for each sample. Then, MALDB performs data analysis on unlabeled dataset and queries the useful unlabeled samples based on different characteristics of two branches to iteratively expand the training dataset and improve the performance of classifier. Finally, MALDB combines multiple level information from multiple hidden layers of BCNNs to further improve the stability of sample selection. The experiments are conducted on five extensively used datasets, Fashion-MNIST, Cifar-10, SVHN, Scene-15 and UIUC-Sports, the experimental results demonstrate the validity of our proposed MALDB.

scholarly journals Research on Improved Intelligent Control Processes Based on Three Kinds of Artificial Intelligence

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1042
Author(s):  
Jingwei Liu ◽  
Tianyue Li ◽  
Jiaming Chen ◽  
Fangling Zuo
Keyword(s):  
Artificial Intelligence ◽  
Low Cost ◽  
Control Parameters ◽  
Chemical Production ◽  
Industrial Control ◽  
Control Processes ◽  
The Stability ◽  
Tuning Methods ◽  
Classical Control ◽  
Online Tuning

Autotuning and online tuning of control parameters in control processes (OTP) are widely used in practice, such as in chemical production and industrial control processes. Better performance (such as dynamic speed and steady-state error) and less repeated manual-tuning workloads in bad environments for engineers are expected. The main works are as follows: Firstly, a change ratio for expert system and fuzzy-reasoning-based OTP methods is proposed. Secondly, a wavelet neural-network-based OTP method is proposed. Thirdly, comparative simulations are implemented in order to verify the performance. Finally, the stability of the proposed methods is analyzed based on the theory of stability. Results and effects are as follows: Firstly, the proposed control parameters of online tuning methods of artificial-intelligence-based classical control (AI-CC) systems had better performance, such as faster speed and smaller error. Secondly, stability was verified theoretically, so the proposed method could be applied with a guarantee. Thirdly, a lot of repeated and unsafe manual-based tuning work for engineers can be replaced by AI-CC systems. Finally, an upgrade solution AI-CC, with low cost, is provided for a large number of existing classical control systems.

Grain-Coarsening Resistance and The Stability of Second-Phase Dispersions in Rapidly Solidified Steels

1981 ◽  
Vol 8 ◽  
Author(s):  
G. B. Olson ◽  
H. C. Ling ◽  
J. S. Montgomery ◽  
J. B. Vander Sande ◽  
M. Cohen
Keyword(s):  
Rare Earth ◽  
Grain Boundary ◽  
Alloy Composition ◽  
Second Phase ◽  
Alloy Development ◽  
Grain Coarsening ◽  
Dispersed Phases ◽  
Grain Boundary Pinning ◽  
The Stability ◽  
Rapidly Solidified

ABSTRACTControl of alloy composition and processing to achieve grain coarsening resistance in rapidly solidified alloys is examined via the theory of grain boundary pinning and particle coarsening. The principles are illustrated for the case of manganese sulfides in steels. A thermodynamic survey of potential stable dispersed phases identifies TiN and rare-earth sulfides as particularly promising for alloy development via rapid solidification.

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