Improvement of Room Temperature Ductility of Ni3Al by Unidirectional Solidification

1990 ◽  
Vol 213 ◽  
Author(s):  
Toshiyuki Hirano ◽  
Sea-Sung Chung ◽  
Yoshinao Mishima ◽  
Tomoo Suzuki
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Tensile Elongation ◽  
Growth Direction ◽  
Al Alloy ◽  
Transgranular Fracture ◽  
Zone Method ◽  
Room Temperature Ductility ◽  
The Matrix ◽  
Temperature Fracture

ABSTRACTWe present the new promising method to improve the ductility of intermetallic compound, Ni3Al. Stoichiometric and Alrich Ni3A1 were unidirectionally grown at the growth rate of 24 mm/h by a floating zone method (FZ-UDS). The stoichiometric Ni3Al had a columnar-grained and single phase structure, whereas the Al-rich Ni3Al had a Ni3Al matrix with martensite-like precipitates. These alloys exhibited a large tensile elongation along the growth direction at room temperature. Fracture mode is a complete transgranular fracture in the stoichiometric Ni 3Al alloy, and a mixture of transgranular fracture of the matrix and cleavage of the martensite-like precipitates with cracking at the phase boundary in the Al-rich Ni3Al alloys.

Microstructural Evolution and Room Temperature Fracture Toughness of a Nb-Ti-Si-Cr-Al-Hf-Y Alloy Prepared by Directional Solidification

2019 ◽  
Vol 971 ◽  
pp. 59-64
Author(s):  
Guan Qun Zhuo ◽  
Lin Fen Su ◽  
Kai Yong Jiang
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Directional Solidification ◽  
Microstructural Evolution ◽  
Room Temperature ◽  
Growth Direction ◽  
Withdrawal Rate ◽  
The Matrix ◽  
Temperature Fracture

The Nb-24Ti-12Si-14Cr-2Al-2Hf-0.1Y (at.%) alloys were fabricated by directional solidification with selected withdrawal rate 1.2 and 18 mm/min, followed by a heat treatment at 1375 °C for 10 h. The microstructure of directional solidified samples were composed of NbSS, Cr2Nb and eutectics (NbSS+Nb5Si3), aligning with the growth direction. After heat treatment, the NbSS in the eutectic structures and NbSS dendrites were connected to form the matrix, and the silicide and Cr2Nb tended to spheroidize. The sample prepared by higher withdrawal rate plus heat treament shows higher average KQ values. The results suggested that the Nb-Si based alloy showed higher room-temperature fracture toughness when the microstructure consists of continuous NbSS distributed with finer Nb5Si3 and Cr2Nb.

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

1996 ◽  
Vol 54 ◽  
pp. 548-549
Author(s):  
Ian M. Anderson
Keyword(s):  
Room Temperature ◽  
Iron Aluminide ◽  
Low Density ◽  
Intermetallic Alloys ◽  
Practical Applications ◽  
Alloying Additions ◽  
Site Distribution ◽  
Good Corrosion Resistance ◽  
Room Temperature Ductility ◽  
The Matrix

B2-ordered iron aluminide intermetallic alloys exhibit a combination of attractive properties such as low density and good corrosion resistance. However, the practical applications of these alloys are limited by their poor fracture toughness and low room temperature ductility. One current strategy for overcoming these undesirable properties is to attempt to modify the basic chemistry of the materials with alloying additions. These changes in the chemistry of the material cannot be fully understood without a knowledge of the site-distribution of the alloying elements. In this paper, the site-distributions of a series of 3d-transition metal alloying additions in B2-ordered iron aluminides are studied with ALCHEMI.A series of seven alloys of stoichiometry Fe50AL45Me5, with Me = {Ti, V, Cr, Mn, Co, Ni, Cu}, were prepared with identical heating cycles. Microalloying additions of 0.2% B and 0.1% Zr were also incorporated to strengthen the grain boundaries, but these alloying additions have little influence on the matrix chemistry and are incidental to this study.

Effect of Trace Boron Addition on the Microstructure and Tensile Elongation of Ti2AlNb-Based Orthorhombic Titanium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1439-1444
Author(s):  
Masuo Hagiwara ◽  
Tomoyuki Kitaura
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Tensile Elongation ◽  
Boron Addition ◽  
Grain Sizes ◽  
Solution Treated Condition ◽  
Room Temperature Ductility ◽  
Solution Treated ◽  
Treated Condition ◽  
Orthorhombic Titanium

The grain sizes of two kinds of orthorhombic alloys, namely (O+B2) Ti-22Al-11Nb-2Mo -1Fe and (O+2) Ti-27.5Al-13Nb have been successfully reduced by the addition of trace boron (B) (less than 0.12 wt.%). For example, the grain size in the B2 solution-treated condition was reduced from 1 mm to 80 m by the addition of 0.05% B for both alloys. The tensile elongation of Ti-22Al-11Nb-2Mo-1Fe at room temperature and 650C was increased from 0.3% to 4.3%, and from 8.2% to 30.3%, respectively, by the addition of 0.10% B. Ti-27.5Al-13Nb also showed an improved room temperature ductility by the minor B addition.

The Room Temperature and Elevated Temperature Fracture Toughness Response of Alloy A-286

1978 ◽  
Vol 100 (2) ◽  
pp. 195-199 ◽  
Author(s):  
W. J. Mills
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Second Phase ◽  
Surface Micromorphology ◽  
Second Phase Particles ◽  
The Matrix ◽  
Temperature Fracture ◽  
Increasing Temperature ◽  
Base Superalloy

The elastic-plastic fracture toughness (JIc) response of precipitation strengthened Alloy A-286 has been evaluated by the multi-specimen R-curve technique at room temperature, 700 K (800°F) and 811 K (1000°F). The fracture toughness of this iron-base superalloy was found to decrease with increasing temperature. This phenomenon was attributed to a reduction in the materials’s strength and ductility at elevated temperatures. Electron fractographic examination revealed that the overall fracture surface micromorphology, a duplex dimple structure coupled with stringer troughs, was independent of test temperature. In addition, the fracture resistance of Alloy A-286 was found to be weakened by the presence of a nonuniform distribution of second phase particles throughout the matrix.

Deformation of Polysynthetically Twinned (PST) Crystals of TiAl in Tension and Compression at Room Temperature

1990 ◽  
Vol 213 ◽  
Author(s):  
H. Inui ◽  
A. Nakamura ◽  
M. Yamaguchi
Keyword(s):  
Electron Microscope ◽  
Room Temperature ◽  
Tensile Axis ◽  
Tensile Elongation ◽  
Deformation Mechanisms ◽  
Deformation Structures ◽  
Room Temperature Ductility ◽  
Tension And Compression

ABSTRACTPolysynthetically twinned (PST) crystals of TiAl have been grown and deformed in tension and compression at room temperature. A room temperature tensile elongation of 12.8% which is far larger than any other reported values of room temperature ductility was obtained for a specimen whose tensile axis is inclined at 51° to the lamellar boundaries. Deformation mechanisms of PST crystals of TiAl are discussed on the basis of the results of electron microscope observations of deformation structures.

Ductilization of a Ni3(Si,Ti) Intermetallic Alloy by Addition of Interstitial Type Elements

2011 ◽  
Vol 409 ◽  
pp. 321-326
Author(s):  
Hisashi Kosaka ◽  
Yasuyuki Kaneno ◽  
Takayuki Takasugi
Keyword(s):  
Fracture Surface ◽  
Fracture Mode ◽  
Room Temperature ◽  
Tensile Ductility ◽  
Tensile Elongation ◽  
Intermetallic Alloy ◽  
Intermediate Temperature ◽  
Transgranular Fracture ◽  
Ti Alloy ◽  
Brittle Intergranular Fracture

The effect of a concomitant doping of interstitial type elements boron (B) and carbon (C), and boron (B) and nitrogen (N) on tensile properties of a Ni3(Si,Ti) intermetallic alloy was investigated in the temperature range between room temperature and 973 K. It was found that the concomitant doping of (C/B) and (N/B) remarkably improved the intermediate-temperature tensile elongation of the Ni3(Si,Ti) alloy compared with the simple doping of B or C. It was also shown that the fracture surface of the alloy doped with (C/B) and (N/B) exhibited the ductile transgranular fracture mode while that of the alloy doped with only B showed a brittle intergranular fracture mode at 773 K. These results clearly indicate that the concomitant doping of the interstitial type elements are useful for improving the intermediate-temperature tensile ductility of the Ni3(Si,Ti) alloy.

Processing and Mechanical Properties of RuAl-Based Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1469-1474 ◽  
Author(s):  
T.D. Reynolds ◽  
M. Acosta ◽  
David R. Johnson
Keyword(s):  
Fracture Toughness ◽  
Cyclic Oxidation ◽  
Room Temperature ◽  
Single Phase ◽  
Tensile Ductility ◽  
Tensile Behavior ◽  
Directionally Solidified ◽  
Two Phase ◽  
Heat Treated ◽  
Temperature Fracture

Alloys of Ru-Al-Cr with compositions between Ru-10Al-35Cr and Ru-3Al-39Cr (at.%) were directionally solidified and heat treated to produce single phase hcp-Ru(Cr,Al) and two phase B2-hcp microstructures. The room temperature fracture toughness, tensile behavior, and cyclic oxidation behavior at 1100°C were investigated and compared to previous results measured from RuAl and Ru-Al-Mo alloys. For microstructures consisting of a Ru(Cr,Al) matrix with fine RuAl precipitate, a good room temperature fracture toughness, tensile ductility, and oxidation resistance at 1100°C were measured.

Effect of compositional modification on ductility of B2 phase in Ti–Al–Nb intermetallic alloy

2002 ◽  
Vol 17 (10) ◽  
pp. 2611-2614 ◽  
Author(s):  
Feng Tang ◽  
Masuo Hagiwara
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Phase State ◽  
Intermetallic Alloy ◽  
Chemical Compositions ◽  
Intermetallic Alloys ◽  
Two Phase ◽  
Room Temperature Ductility ◽  
Single Phase State ◽  
B2 Phase

Room-temperature ductility of two Ti–Al–Nb intermetallic alloys with close chemical compositions was investigated by tensile testing. The two alloys' ductilities in the B2 single-phase state were significantly different, which indicated that the ductility of B2 phase state was sensitive to the chemical composition. The alloy with more ductile B2 phase exhibited higher ductility in O + B2 two-phase state.

Microstructure Design for Enhancement of Room-temperature Ductility in Multi-component TiAl Alloys

MRS Advances ◽  
2019 ◽  
Vol 4 (25-26) ◽  
pp. 1523-1529 ◽  
Author(s):  
Ryosuke Yamagata ◽  
Yotaro Okada ◽  
Hideki Wakabayashi ◽  
Hirotoyo Nakashima ◽  
Masao Takeyama
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Significant Contribution ◽  
Volume Fraction ◽  
Microstructure Design ◽  
Tial Alloys ◽  
Volume Fractions ◽  
Β Phase ◽  
Room Temperature Ductility

AbstractEffects of microstructure constituents of α2-Ti3Al/γ-TiAl lamellae, β-Ti grains and γ grains, with various volume fractions on room-temperature ductility of γ-TiAl based alloys have been studied. The ductility of the alloys containing β phase of about 20% in volume increases to more than 1% as the volume fraction of γ phase increases to 80%. However, γ single phase alloys show very limited ductility of less than 0.2%. The present results, thus, confirmed the significant contribution of β phase to enhancement of the room-temperature ductility in multi-component TiAl alloys.

Fabrication and Characterization of TiNi/AL Smart Composites

2003 ◽  
Vol 785 ◽  
Author(s):  
Gyu Chang Lee ◽  
Jun Hee. Lee ◽  
Young Chul Park
Keyword(s):  
Composite Material ◽  
Shape Memory ◽  
Yield Stress ◽  
Room Temperature ◽  
Volume Fraction ◽  
Matrix Material ◽  
Al Alloy ◽  
Alloy Matrix ◽  
Strain Behavior ◽  
The Matrix

ABSTRACTAn attempt was made to fabricate composite material of an Al alloy matrix reinforced by TiNi shape memory fiber using a hot-press method and to investigate its microstructures and mechanical properties. The analysis of SEM and EDS showed that the composite material had good interface bonding. The stress-strain behavior of the composite material was evaluated at room temperature and 363 K as a function of pre-strain, and it showed that the yield stress at 363 K is higher than that at room temperature. It is also found that the yield stress of the composite material increased with increasing the amount of pre-strain and depended on the volume fraction of the fiber and heat treatment. The smartness of the composite could be given due to the shape memory effect of the TiNi fiber, which generated compressive residual stress in the matrix material when heated after being pre-strained. Microstructural observation revealed that interfacial reactions occurred between the matrix and fiber, creating two intermetallic layers.

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