oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Effects of gravity on the microstructure of Zr41Ti14-Cu12.5Ni10Be22.5 bulk glass forming alloy
Gong Li,Zaiji Zhan,Limin Wang,Limin Cao,Liling Sun,Daoyang Dai,Jun Zhang,Wenkui Wang
Chinese Science Bulletin , 2001, DOI: 10.1007/BF02900476
Abstract: The ZrTiCuNiBe alloy is melt and solidified by Bridgman unidirectional solidification on two gravity field orientations (the gravity field orientation is parallel and opposite to solidification direction). Effects of gravity on morphology and microstructure are investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). When gravity field orientation is parallel to solidification direction, less needle-like primary phase is embedded in a matrix eutectic; when gravity field orientation is opposite to solidification direction, a large amount of coarser needle-like primary phases were observed.
Effects of gravity on the microstructure of Zr41Ti14-Cu12.5Ni10Be22.5 bulk glass forming alloy

Gong Li,Zaiji Zhan,Limin Wang,Limin Cao,Liling Sun,Daoyang Dai,Jun Zhang,Wenkui Wang,

科学通报(英文版) , 2001,
Abstract: The ZrTiCuNiBe alloy is melt and solidified by Bridgman unidirectional solidification on two gravity field orientations (the gravity field orientation is parallel and opposite to solidification direction). Effects of gravity on morphology and microstructure are investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). When gravity field orientation is parallel to solidification direction, less needle-like primary phase is embedded in a matrix eutectic; when gravity field orientation is opposite to solidification direction, a large amount of coarser needle-like primary phases were observed.
Microstructure evaluation of the Al-Ti alloy with magnesium addition  [PDF]
K. Labisz,L.A. Dobrzański,R. Maniara,A. Olsen
Journal of Achievements in Materials and Manufacturing Engineering , 2011,
Abstract: Purpose: Effects of magnesium additions to Al alloy with 2% Ti addition on the microstructure, phase morphology and distribution and mechanical properties were investigated. Here are presented mainly microstructure changes after solution heat treatment concerning mainly grain uniformity and intermetallic phases of the aluminium – titanium alloy with a content of 2 and 4 % of magnesium addition. The purpose of this work was also to determine the solution heat treatment conditions of the investigation alloys.Design/methodology/approach: The reason of this work was to determine the heat treatment parameters influence, particularly SHT temperature and time onto the changes of the microstructure of the investigated material, as well to determine which intermetallic phases occur after the heat treatment performed, and how is the particles morphology in as cast state compared to structure after heat treatment.Findings: After solution heat treatment for 4 hours the structure changes in a significant way. The grains are larger and no more uniform as in the as cast state. The most stable intermetallic in the Al-Ti system is the Al3Ti phase. The solution heat treatment time should be greater than 4 hours to ensure a proper solution of titanium and magnesium in the Al-α solid solution.Research limitations/implications: The investigated aluminium samples were examined metallographically using optical microscope with different image techniques, scanning electron microscope and also analyzed using a Vickers micro-hardness tester, also EDS microanalysis was carried out.Practical implications: As an implication for the practice an alloy can be developed with increased properties, which could be of great interest for the automotive or aerospace industry. There are existing many different investigation areas and the knowledge found in this research shows one of interesting investigation direction.Originality/value: The combination of light weight and high strength achieved in the Al-Ti alloys is very attractive for aerospace and automotive industries. Addition of magnesium into the Al-Ti alloy could help also to reveal the existence new unknown phases.
Microstructure and mechanical properties of the Al-Ti alloy with calcium addition  [PDF]
L.A. Dobrzański,K. Labisz,A. Olsen
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: In this paper there are presented the investigation results of mechanical properties and microstructure with intermetallic phases of the aluminium – titanium alloy with a defined content of Ca addition. The purpose of this work was also to determine the heat treatment conditions for solution heat treatment of the investigation alloys.Design/methodology/approach: The reason of this work was to determine the heat treatment influence, particularly solution heat treatment time to the changes of the microstructure, as well to determine which intermetallic phases occur after the heat treatment performed, and how is the morphology of these particles.Findings: After solution heat treatment for 4 hours the structure changes in a way, that the grains are larger and no more uniform as showed before. The most stable intermetallic in the Al-Ti system is the Al3Ti phase. The solution heat treatment time should be greater than 4 hours to ensure a proper solution of titanium and calcium in the Al-α solid solution.Research limitations/implications: The investigated aluminium samples were examined metallographically using optical microscope with different image techniques, SEM, TEM and analyzed using a Vickers micro-hardness tester, also EDS microanalysis was made.Practical implications: As an implication for the practice a new alloy can be developed, some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction.Originality/value: The combination of light weight and high strength Ti-based alloys is very attractive for aerospace and automotive industries. Furthermore, the presence of calcium can bring into existence new unknown phases as well can enhance the thermal stability of ternary Al-Ti-Ca alloy because of its higher melting point then Al-Ti.
Microstructure and mechanical properties of the Al-Ti alloy with cerium addition  [PDF]
L.A. Dobrzański,K. Labisz,R. Maniara,A. Olsen
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: In this work there are presented the investigation results of mechanical properties and microstructure concerning mainly intermetallic phases of the aluminium – titanium alloy with a defined content of 2 and 4 % of cerium addition. The purpose of this work was also to determine the heat treatment conditions for solution heat treatment of the investigation alloys.Design/methodology/approach: The reason of this work was to determine the heat treatment influence, particularly solution heat treatment time to the changes of the microstructure, as well to determine which intermetallic phases occur after the heat treatment performed, and how is the morphology of these particles.Findings: After solution heat treatment for 4 hours the structure changes. The grains are larger and no more uniform as showed before. The most stable intermetallic in the Al-Ti system is the Al3Ti phase. The solution heat treatment time should be greater than 4 hours to ensure a proper solution of titanium and cerium in the Al-α solid solution.Research limitations/implications: The investigated aluminium samples were examined metallographically using optical microscope with different image techniques, scanning electron microscope and also analyzed using a Vickers micro-hardness tester, also EDS microanalysis was made.Practical implications: As an implication for the practice a new alloy can be developed, some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction.Originality/value: The combination of light weight and high strength Ti-based alloys is very attractive for aerospace and automotive industries. Furthermore, the presence of calcium cerium into existence new unknown phases as well can enhance the thermal stability of ternary Al-Ti-Ce alloy because of its higher melting point then Al-Ti.
Microstructure of Si-Al-Y Co-deposition Coatings on an Nb-Ti-Si Based Ultrahigh Temperature Alloy  [PDF]
ZHANG Chao-Feng, GUO Xi-Ping
无机材料学报 , 2010, DOI: 10.3724/sp.j.1077.2010.01209
Abstract: The oxidation-resistant Si-Al-Y co-deposition coatings on a Nb-Ti-Si based ultrahigh temperature alloy were prepared by halide activated pack cementation processes. SEM, EDS and XRD analyses were used to study the influences of the holding temperature and the content of Al in pack mixtures on the microstructural formation of the coatings. The results show that the coatings prepared with the pack mixture of 10Si-10Al-3Y-5NaF-72Al2O3 (wt%) at different temperatures (1050 1080 nd 1150 respectively) have a similar structure, consisting of a (Nb,X)Si2(X represents Ti, Cr and Hf elements) outer layer, a (Nb, X)5Si3 mid layer, a sub-inner layer composed of (Cr,Al)2(Nb,X) and (Nb,X)Al3 phases, and a very thin inner layer consisting of (Nb,X)2Al phase. The microstructure of the coatings prepared at 1050 or 10h changes evidently with the content of Al in the pack mixtures (10Si-xAl-3Y-5NaF-(82-x)Al2O3 (wt%) (x=10, 15, 20, respectively)). Increasing the content of Al in the pack mixture to 15wt%, the constituent phases of the mid layer of the coating change into (Nb,X)Al3 and (Nb,X)5Si3, but the constituent phases remain unchanged in the outer layer, sub-inner layer and inner layer in the coating. The main constituent phases of the outer layer of the coating prepared with the pack mixture containing 20wt% Al are (Nb,X)Si2 and (Nb,X)3Si5Al2, while the constituents phases of the other layers in this coating are the same as those in the coating prepared with the pack mixture containing 15wt% Al. The scale developed on Si-Al-Y co-deposition coating which was prepared with 10Si-15Al-3Y-5NaF-67Al2O3 (wt%) pack mixture at 1050 or 10h, upon oxidation at 1250 or 0.5h, is about 10μm thick, and composed of Al2O3, TiO2 and SiO2.
Prediction of Microstructure Evolution in Hot Backward Extrusion of Ti-6Al-4V Alloy
Jong-Taek Yeom,Jeoung Han Kim,Jae-Keun Hong,Nho-Kwang Park,Chong Soo Lee
Journal of Metallurgy , 2012, DOI: 10.1155/2012/989834
Abstract: Microstructure evolution of Ti-6Al-4V alloy during hot backward extrusion process was simulated with the combined approaches of finite element method (FEM) and microstructure prediction model. From experimental analysis, it can be found that the change of microstructure during hot forming process of titanium alloy has a close relation to / phase transformation and grain growth behaviour. A microstructure prediction model was established by considering the change of volume fractions and grain size of both phases varying with process variables and then implemented into the user-defined subroutine of FEM analysis. In order to demonstrate the reliability of the model, the volume fraction and grain size of primary phase during the hot backward extrusion process of Ti-6Al-4V alloy were simulated. The simulation results were compared with the experimental ones.
Superplastic Forming and Diffusion Bonding for Sandwich Structure of Ti-6Al-4V Alloy
Wenbo HAN,Kaifeng ZHANG,Guofeng WANG,Xiaojun ZHANG,
Wenbo HAN
,Kaifeng ZHANG,Guofeng WANG and Xiaojun ZHANGSchool of Materials Science and Engineering,Harbin Institute of Technology,Harbin,ChinaProf.,Ph.D.

材料科学技术学报 , 2005,
Abstract: Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6Al-4V sheet material. The sandwich structure of Ti-6Al-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.
Effect of preparation methods on microstructure and properties of W-10%Ti alloy
制备方法对W-10%Ti合金组织性能的影响

WANG Qingxiang,FAN Zhikang,YANG Yi,
王庆相
,范志康,杨怡

材料研究学报 , 2009,
Abstract: By using high--purity tungsten powders, titanium powders and TA2 Ti sheet as the raw materials, W--10%Ti alloys were prepared by infiltration and liquid--phase sintering respectively. The density and impurity content of C, N and O in W--10\%Ti alloy were measured. The morphology, composition and microstructure were characterized. The results show that W--10\%Ti alloy prepared by infiltration has a relative density of above 94% and is mainly consisted of Ti--rich $\beta$ solid solution, while the relative density of W--Ti prepared by liquid phase sintering is about 90% and the microstructure is uniform. The W--Ti alloys prepared by both methods have low impurity contents. The formation mechanism of W--10\%Ti alloy by liquid phase sintering was discussed as well.
Effects of Heat Treatment on the Transformation Temperature and the Microstructure of Ni-Ti-Nb Shape Memory Alloy
Yufeng ZHENG,Wei CAI,Yongqian WANG,Yichun LUO,Liancheng ZHAO,

材料科学技术学报 , 1998,
Abstract: The effects of heat treatment on the phase transformation temperature and the microstructure of Ni-Ti-Nb alloy have been investigated by means of R-T method, TEM and EPMA. With the increase of annealing temperature, cooling rate and ageing temperature, the Ms temperature increases. TEM observations show no new precipitated phase was found in the B2 parent phase after heat treatment, but EPMA shows the content of Ni (or Ni/Ti ratio) in the B2 matrix changed. The main reason for the change of transformation temperature lies in the change of the matrix composition (or Ni/Ti ratio) with the variation of heat treatment procedure.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.