Alignment of the lamellar orientation of multi-component TiAl alloys by directional solidification (DS) and mechanical properties of DS ingots

2002 ◽  
Vol 753 ◽  
Author(s):  
Y. Omiya ◽  
S. Muto ◽  
T. Yamanaka ◽  
D. R. Johnson ◽  
H. Inui ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Directional Solidification ◽  
Lamellar Structure ◽  
Growth Direction ◽  
Alloying Elements ◽  
Tial Alloys ◽  
Creep Properties ◽  
Lamellar Orientation ◽  
Loading Axis ◽  
Better Than

ABSTRACTBy using an appropriately oriented seed from the TiAl-Si system (Ti-43Al-3Si), the TiAl/Ti3Al lamellar structure has been successfully aligned parallel to the growth direction for TiAl ingots of the Ti-Al-Nb, Ti-Al-Nb-Si, Ti-Al-Ta-Si systems on the basis of the recently proposed method to predict the appropriate compositions. The Al equivalents for Nb and Ta are reevaluated in order to extend the proposed method to large addition (above a several at. %) of these alloying elements. These DS ingots with the lamellar structure all aligned parallel to the loading axis exhibit creep properties far better than conventionally produced TiAl ingots so far reported.

Mechanical properties of NiAl-Mo composites produced by specially controlled directional solidification

2012 ◽  
Vol 1516 ◽  
pp. 255-260 ◽  
Author(s):  
G. Zhang ◽  
L. Hu ◽  
W. Hu ◽  
G. Gottstein ◽  
S. Bogner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Directional Solidification ◽  
Creep Resistance ◽  
Room Temperature ◽  
Growth Direction ◽  
Nominal Composition ◽  
Potential Candidate ◽  
In Situ Composites

ABSTRACTMo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

Microstructure and Mechanical Properties of Ti-6Al-4V Alloy Samples Fabricated by Selective Laser Melting

2018 ◽  
Vol 770 ◽  
pp. 179-186 ◽  
Author(s):  
Jing Bo Gao ◽  
Xiao Li Zhao ◽  
Ju Kun Yue ◽  
Meng Chao Qi ◽  
De Liang Zhang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Crystal Growth ◽  
Yield Strength ◽  
Selective Laser Melting ◽  
Lamellar Structure ◽  
Growth Direction ◽  
Laser Melting ◽  
Α Phase ◽  
Dog Bone

Ti-6Al-4V (wt%) alloy samples with dog-bone and box shapes respectively were fabricated by selective laser melting (SLM). The microstructures and mechanical properties of the 3D printed Ti-6Al-4V samples with and without heat treatment were characterized and tested. The microstructures of the as-fabricated dog-bone shaped samples were mainly composed of acicular α’ phase. After annealing at 700°C, the acicular α’ phase changed into an α/β lamellar structure. After solution treatment at 955°C, water quenching and aging at 550°C, the microstructure was mainly composed of primary α phase and α/β lamellar structure. The optimum heat treatment is annealing, and the mechanical properties of the annealed sample are as follows: yield strength: 1015 MPa, ultimate tensile strength (UTS): 1083 MPa and elongation to fracture: 7.9%. The microstructures of the box-shaped samples after annealing mainly consist of α phase and α/β lamellar structure. When stretched along the direction parallel to the crystal growth direction, the yield strength and UTS of the sample are 1054 and 1090 MPa，and its elongation to fracture is 6.3%. When stretched along the direction perpendicular to the crystal growth direction, the yield strength and UTS of the sample are 1019 and 1068 MPa respectively, and its elongation to fracture is 8.7%.

Deformation of Diffusion-Bonded Bi-Pst and Directionally Solidified Crystals of TiAl

1996 ◽  
Vol 460 ◽  
Author(s):  
K. Kishida ◽  
D. R. Johnson ◽  
Y. Shimada ◽  
Y. Masuda ◽  
H. Inui ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Diffusion Bonding ◽  
Flow Behavior ◽  
Lamellar Microstructure ◽  
Growth Direction ◽  
Current Status ◽  
Directionally Solidified ◽  
Lamellar Orientation ◽  
Columnar Grain ◽  
And Diffusion

ABSTRACTWith a data base now available on the microstructural characteristics and the deformation, fracture and macroscopic flow behavior of polysynthetically twinned (PST) crystals of γ/α2 TiAl-base alloys, an approach to achieve a good combination of strength, ductility and toughness in γ/α2 TiAl-base alloys was proposed using directional solidification (DS) techniques to produce a columnar grain material with the lamellar orientation aligned parallel to the growth direction. Such alignment of the lamellar microstructure was recently accomplished in γ/α2 TiAl-base alloys of near equiatomic compositions using an appropriately oriented seed crystal from the Ti-Al-Si system.At the same time, bi-PST crystals, each containing a planar boundary parallel to the loading axis were prepared by directional solidification and diffusion bonding of two PST crystals. Such bi-PST crystals were deformed in tension at room temperature and their deformation behavior was examined in terms of the compatibility requirements imposed at the grain boundary and the interaction of the two component PST crystals.In this paper, (i) the current status of our DS processing efforts, (ii) some results of microscopic characterization of grain boundaries in diffusion bonded bi-PST crystals and (iii) results of deformation experiments of bi-PST crystals prepared by DS processing and diffusion bonding, will be reported.

Development of Magnesium Based Alloys for High Temperature Applications

2011 ◽  
Vol 673 ◽  
pp. 179-184 ◽  
Author(s):  
Uma Thanu Subramonia Pillai ◽  
Amirthalingam Srinivasan ◽  
Krishnamorthy Raghukandan ◽  
Ballembettu Chandrasekhar Pai
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Corrosion Behavior ◽  
Creep Resistance ◽  
Alloying Elements ◽  
Az91 Alloy ◽  
Thermally Stable ◽  
Creep Properties ◽  
Temperature Applications

Individual and combined additions of elements like Si, Sb, Sr are carried out to AZ91 alloy and its microstructure, mechanical properties especially creep properties and corrosion behavior are investigated. In general, additions of the above elements improve the mechanical properties. Further, the results show these alloying elements introduce thermally stable intermetallics and thereby improve the creep performance. Among various additions, Sb addition provides highest creep resistance. With the Si and Sr additions, the corrosion resistance of AZ91 alloy is improved. Detailed micro-mechanisms are also studied and they are correlated with the properties studied.

Effects of alloying elements on creep of TiAl alloys with a fine lamellar structure

2002 ◽  
Vol 50 (6) ◽  
pp. 1307-1318 ◽  
Author(s):  
J.N. Wang ◽  
J. Zhu ◽  
J.S. Wu ◽  
X.W. Du
Keyword(s):  
Lamellar Structure ◽  
Alloying Elements ◽  
Tial Alloys

Creep Properties of Alborex Reinforced AZ31 Matrix Mg Composites Containing Ag

2007 ◽  
Vol 539-543 ◽  
pp. 983-987
Author(s):  
Sung Doo Hwang ◽  
Yong Ha Park ◽  
Dae Hyun Song ◽  
Man Sik Lee ◽  
Kyung Mok Cho ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Squeeze Casting ◽  
Matrix Composites ◽  
Casting Method ◽  
Alloy Matrix ◽  
Creep Properties ◽  
High Temperature Properties ◽  
Az31 Mg Alloy ◽  
Better Than

AZ31 Mg alloy matrix composites were fabricated by squeeze casting method to improve high temperature properties in this study. The results showed that Mg composites reinforced with Alborex and Ag revealed improved high temperature properties and mechanical properties compared with Mg alloys. High temperature hardness and flexural strength were increased with reinforcement of Alborex, and further increase was obtained with addition of Ag. Also, Alborex reinforced AZ31 containing Ag Mg matrix composite exhibited greater improvement on creep properties. Therefore Mg composites reinforced with Alborex containing Ag were better than those reinforced with Alborex in mechanical properties and high temperature properties.

Effects of Forming Processing on Mechanical Properties of Ti-48Al-2Mn-2Nb Intermetallics

2005 ◽  
Vol 297-300 ◽  
pp. 471-476 ◽  
Author(s):  
Wen Zhe Chen ◽  
Kai Ping Peng ◽  
Kuang Wu Qian ◽  
Hai Cheng Gu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Tial Alloy ◽  
Spray Deposition ◽  
Tensile Elongation ◽  
Hot Isostatic Pressing ◽  
Compressive Properties ◽  
Tial Alloys ◽  
Deformation And Fracture ◽  
Better Than

Ti-48Al-2Mn-2Nb alloy was produced by “centrifugal spray deposition” (CSD), and then hot isostatic pressing (HIP) was employed to remove the porosity formed by CSD. The effects of CSD and HIP processing on the mechanical properties and microstructure of the TiAl alloy were investigated. The results show that the CSD and HIP processing can both improve the strength, plasticity of the TiAl alloy, and the tensile elongation values of the CSD or HIP samples are around 3%, which are better than those of as-cast TiAl alloys in room temperature. Especially, they show more excellent compressive properties at ambient temperature with a compressive ratio of 33.8% and compressive strength of 2210MPa for the CSD samples, and a compressive ratio of 37.8% and compressive strength of 2348MPa for the HIP samples. The CSD processing also improves the fracture toughness of TiAl alloy, which is much higher than that of the HIP processing, while the HIP processing seems to be beneficial the ductility and plasticity as having a duplex structure. The effects of CSD and HIP processing on microstructure and properties of TiAl alloys are discussed to understand the deformation and fracture process of the alloy.

Effect of Alloying Elements on Microstructure and Mechanical Properties of High Temperature Die Material DM02 Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1257-1260
Author(s):  
Jin Xia Song ◽  
Qing Li ◽  
Cheng Bo Xiao ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Strength ◽  
Alloying Elements ◽  
Strengthening Effect ◽  
Die Material ◽  
High Temperature Tensile ◽  
High Temperature Tensile Properties ◽  
Base Superalloy ◽  
Better Than

The effect of Ta, Nb, Hf and Zr on the microstructure and high temperature tensile properties of DM02 alloy, which is a novel developed Ni base superalloy for high temperature die material, had been studied in this paper. The results showed that the four alloying elements affect the composition and morphology of carbides obviously, and have almost no effect on the morphology and size of γ´ phase in DM02 alloy. 0.5-1wt% Hf make the morphology of MC carbide change from bone-like to blocky and inhibit the formation of primary M6C carbide, thus improve the ductility of DM02 alloy, while 0.1wt% Zr has no similar effect. The strengthening effect of 3wt% Ta is better than that of 1.5wt% Nb. DM02 alloy with 3wt% Ta and 0.5wt% Hf has high strength and good ductility at 1050°C.

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