Effect of Heat Treatment and Composition on Grain Size and Lamellar Spacing of a Lamellar TiAl Alloy

2011 ◽  
Vol 335-336 ◽  
pp. 774-778
Author(s):  
Xia Chang ◽  
Xiao Bin Zhang ◽  
Ji Zhang
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Lamellar Spacing ◽  
Lamella Spacing ◽  
Transmission Electron ◽  
Before And After ◽  
Individual Lamella ◽  
Fully Lamellar

The article presents the results of optical microscopy, scanning electron microscopy (SEM), Transmission Electron Microscope (TEM) conducted on a Ti–46.5Al–2.5V-1.0Cr–0.3Ni alloy before and after different heat treatments. Heat treatment of the alloy at 1340°C followed by cooling leads to the formation of the fully lamellar microstructure which consists of γ lamellae mostly and of small amount of α2 lamellae. The cooling rate of 50°C/min in alloy tcx1-G produced an optimal microstructure. This cooling rate generated finest lamellae with the smallest individual lamella spacing among the alloys.

Effect of Heat Treatment on the Microstructure and Property of TiAl Alloys Prepared by Gas Atomization Powders

2013 ◽  
Vol 747-748 ◽  
pp. 497-501
Author(s):  
Na Liu ◽  
Zhou Li ◽  
Guo Qing Zhang ◽  
Hua Yuan ◽  
Wen Yong Xu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Treatment Temperature ◽  
Gas Atomization ◽  
Thermally Induced ◽  
Heat Treated ◽  
Fine Duplex ◽  
Step Heat Treatment

Powder metallurgical TiAl alloy was fabricated by gas atomization powders, and the effect of heat treatment temperature on the microstructure evolution and room tensile properties of PM TiAl alloy was investigated. The uniform fine duplex microstructure was formed in PM TiAl based alloy after being heat treated at 1250/2h followed by furnace cooling (FC)+ 900/6h (FC). When the first step heat treatment temperature was improved to 1360/1h, the near lamellar microstructure was achieved. The ductility of the alloy after heat treatment improved markedly to 1.2% and 0.6%, but the tensile strength decreased to 570MPa and 600MPa compared to 655MPa of as-HIP TiAl alloy. Post heat treatment at the higher temperature in the alpha plus gamma field would regenerate thermally induced porosity (TIP).

Mechanism of Cementite Spheroidization from Different Initial Microstructures in Fe-0.65C-2.33Mn Alloy

2019 ◽  
Vol 815 ◽  
pp. 107-113
Author(s):  
Li Ma ◽  
Tao Jia ◽  
Xiu Hua Gao ◽  
Run Ni
Keyword(s):  
Electron Microscopy ◽  
Cooling Rate ◽  
Local Equilibrium ◽  
Lamellar Spacing ◽  
Initial Structure ◽  
Equilibrium Conditions ◽  
Transmission Electron ◽  
Spheroidizing Annealing ◽  
Carburizing Process ◽  
Scanning Electron

The spheroidization mechanism from different initial microstructures during spheroidizing heat treatment was studied in Fe-0.68C-2.33Mn alloy. Two types of initial microstructures, i.e. pearlite and martensite, were obtained by varying the cooling rate. The microstructure and property evolution during spheroidizing annealing was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The DICTRA software, assuming local equilibrium conditions, was used to simulate the carburizing process of different initial microstructures through different cooling rate. The results indicate that the spheroidization mechanism of cementite was related to the initial microstructures and the smaller lamellar spacing of pearlite inhibited the coarsening of cementite, resulting in the size of cementite smaller than that of martensite as the initial structure.

The Effect of Heat Treatment on the Microstructure of Ti-45Al-5Nb-0.3Y Alloy

2009 ◽  
Vol 614 ◽  
pp. 55-59
Author(s):  
Fan Tao Kong ◽  
Yu Yong Chen
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Lamellar Microstructure ◽  
Air Cooling ◽  
Water Cooling ◽  
Different Temperatures ◽  
Combined Action ◽  
Average Size ◽  
Equiaxed Grains ◽  
Fully Lamellar

Effects of heat treatment on the microstructure of as-cast and as-forged Ti-45Al-5Nb-0.3Y alloy are discussed. The as-cast Ti-45Al-5Nb-0.3Y alloy exhibits a microstructure consisting of fine equiaxed grains which average size is almost 100μm. Phase transformation of as-cast Ti-45Al-5Nb-0.3Y alloy greatly depends upon cooling rate. During furnace cooling, the alloy transform to fully lamellar microstructure. During air cooling, massive transformation predominates. During oil cooling, extremely fine fully lamellar microstructure is formed. During water cooling, ordering α2 phases are primary. Thermo-mechanical treatments, through combined action of hot canned forging and heat treatment, were performed on a Ti-45Al-5Nb-0.3Y alloy to investigate their effect on the microstructure of the alloy. The as-forged Ti-45Al-5Nb-0.3Y alloy is comprised of a large number of dynamic recrystallization (DRX) γ grains, curved and broken lamellae, and a small amount of remnant lamellae. And three different microstructures, duplex (DP), nearly lamellar (NL) and fine fully lamellar (FFL), have been obtained through heat treatment at different temperatures (1320-1370°C), respectively.

The effect of lamellar spacing on the creep behavior of a fully lamellar TiAl alloy

2000 ◽  
Vol 8 (5-6) ◽  
pp. 525-529 ◽  
Author(s):  
C.E. Wen ◽  
K. Yasue ◽  
J.G. Lin ◽  
Y.G. Zhang ◽  
C.Q. Chen
Keyword(s):  
Creep Behavior ◽  
Tial Alloy ◽  
Lamellar Spacing ◽  
Fully Lamellar

Characterization of Ni-P and Ni-P-Al2O3 Heat Treated Layers

2017 ◽  
Vol 1143 ◽  
pp. 26-31
Author(s):  
Lucica Balint ◽  
Gina Genoveva Istrate
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Composite Coatings ◽  
Treatment Temperature ◽  
Initial State ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Before And After

Research has shown the relationship among hardness, usage and corrosion resistance Ni-P-Al2O3 composite coatings on steel support heat treated. The electroless strips were heat treated at 200°C, 300°C, 400°C, 500°C and 600°C. Further studies on corrosion, hardness and usage revealed changes in properties, compared to the initial state, both on the strips coated with Ni-P and the ones coated with Ni-P-Al2O3 composite. The samples have been studied before and after the heat treatment via Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Analysis (EDX) and X-Ray Diffraction (XRD). The results show that untreated Ni-P layers exhibit strong corrosion resistance, while hardness and usage increase with heat treatment temperature, with a peak at 400 °C. Using suspended particles co-deposition, led to new types of layers, some with excellent hardness and usage properties. Corrosion resistance increase with heat treatment. Coating layers can be adjusted to the desired characteristics, by selecting proper parameters for the expected specific results.

scholarly journals The Effect of Cooling Rate on Mechanical Properties of Carbon Steel (St 35)

2014 ◽  
Vol 7 (1) ◽  
pp. 109-118
Author(s):  
Jenan Mohammed Nagie
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Carbon Steel ◽  
Cooling Rate ◽  
Experimental Results ◽  
Heat Treated ◽  
Before And After ◽  
Water Media ◽  
The Relationship

This paper is aimed to study the effect of cooling rate on mechanical properties of Steel 35. Specimens prepared to apply tensile, torsion, impact and hardness tests.Many prepared specimens heat treated at (850ºC) for one hour and subsequently were cooled by three different media [Water-Air-furnace] to show the effect of Medias cooling rate on mechanical properties. Microstructures of all specimens examined before and after heat treatment by an optical microscopy.To figure the phases obtained after heat treatment and its effect on the mechanical properties Experimental results have shown that the microstructure of steel can be changed and significantly improved by varying line cooling rate thus, improving one property will effect on the others because of the relationship between all properties.In water media tensile, torsion and hardness improved while impact results reduced. Air media contributed in improving most of the mechanical properties because of grain size homogeneity. At furnace media ductility and impact improved

Influence of Microstructure and Stress Ratio on Fatigue Crack Propagation in TiAl Alloy

2014 ◽  
Vol 881-883 ◽  
pp. 1330-1333 ◽  
Author(s):  
Yan Rui Zuo ◽  
Zhi Yuan Rui ◽  
Rui Cheng Feng ◽  
De Chun Luo ◽  
Chang Feng Yan
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stress Ratio ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Propagation Resistance ◽  
Crack Propagation Resistance ◽  
Stress Ratios ◽  
Fully Lamellar

Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.

A Detailed Interface Characterization of the Explosively Welded Three-Layered Ti Gr 1/Alloy 400/1.4462 Steel Clads Before and After Heat Treatment

2021 ◽  
pp. 1-9
Author(s):  
Marta Janusz-Skuza ◽  
Agnieszka Bigos ◽  
Łukasz Maj ◽  
Jerzy Morgiel ◽  
Marek Faryna ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Hexagonal Phase ◽  
Cubic Phase ◽  
Interface Zone ◽  
Transmission Electron ◽  
Before And After ◽  
Diffusion Phenomena ◽  
Zone Microstructure

The presented research focused on the microstructural characteristics of explosively welded three-layered Ti Grade (Gr) 1/Alloy 400/1.4462 steel clads before and after heat treatment being of large practical potential. Scanning electron microscopy (SEM) analyses have shown that both interfaces formed between the plates are continuous and without defects. The in-depth examination was dedicated to the upper Ti Gr 1/Alloy 400 interface, located closer to the explosive material, therefore, subjected to more extreme welding conditions. The presence of cubic phase Ti2Ni, hexagonal phase Ni3Ti, and tetragonal phase (Cu x Ni1−x)2Ti were confirmed within the melted zones, which slightly widened due to annealing, being an essential step in the manufacturing of these modern materials. Transmission electron microscopy observations in the nano scale confirmed the preliminary chemical composition analyses collected with energy-dispersive X-ray spectroscopy in SEM. They additionally revealed the interface zone microstructure transformation due to the annealing. It was evidenced that initially mixed phases in the form of grains, after heat treatment formed irregular bands arranged in the following sequence: Alloy 400/Ni3Ti/(Cu x Ni1−x)2Ti/Ti2Ni/Ti Gr 1. A clear segregation of Cu and Ni forming two separate layers was also noticed. These diffusion phenomena may influence the strength of the final product, therefore need further studies regarding the prolonged annealing state.

Microstructures and Creep Properties of Powder Metallurgy Ti-48Al-2Cr-2Nb + W

2007 ◽  
Author(s):  
H. Saari ◽  
S. Bulmer ◽  
D. Y. Seo ◽  
P. Au
Keyword(s):  
Heat Treatment ◽  
Powder Metallurgy ◽  
Lamellar Microstructure ◽  
Controlled Cooling ◽  
Tial Alloys ◽  
Creep Properties ◽  
Rupture Ductility ◽  
Heat Treated ◽  
Fully Lamellar ◽  
Lamellar Interfaces

The microstructures and creep properties at 760 °C and 276 MPa of three powder metallurgy TiAl alloys (Ti-48Al-2Cr-2Nb, Ti-48Al-2Cr-2Nb+0.5W, and Ti-48Al-2Cr-2Nb+1W (atomic percent)) are presented. The results indicate that the addition of W to the base composition, the use of a solution heat treatment combined with controlled cooling (to generate a fully lamellar microstructure), and the use of an aging heat treatment (to generate precipitate particles at the lamellar interfaces) improve creep properties dramatically. The solution heat treated and aged Ti-48Al-2Cr-2Nb+1W alloy has a time to 0.5% strain of 8.3 hours, a time to 1% strain of 46.4 hours, and a creep life of 412 hours with a rupture ductility of 16.9%.

Sign in / Sign up

Export Citation Format

Share Document