Effect of Grain Refinement on Room Temperature Ductility of Ferritic Heat-resistant Alloys Strengthened by NiAl Precipitates

AbstractFe3Al-based alloys exhibit poor room temperature ductility in the as-cast condition. In this study, the effect of grain refinement of the as-cast alloy on room-temperature ductility was investigated. Small melts of Fe-28 at. % Al-5 at. % Cr were inoculated with various alloying additions and cast into a 50- × 30- × 30-mm graphite mold. The resulting ingots were examined metallographically for evidence of grain refinement, and three-point bend tests were conducted on samples to assess the effect on room-temperature ductility. Ductility was assumed to correlate with the strain corresponding to the maximum stress obtained in the bend test. The results showed that titanium was extremely effective in grain refinement, although it severely embrittled the alloy in contents exceeding 1%. Boron additions strengthened the alloy significantly, while carbon additions reduced both the strength and ductility. The best ductility was found in an alloy containing titanium, boron, and carbon.

Download Full-text

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071193 ◽

1973 ◽

Vol 31 ◽

pp. 150-151

Author(s):

J. E. Doherty ◽

A. F. Giamei ◽

B. H. Kear ◽

C. W. Steinke

Keyword(s):

Grain Boundary ◽

Room Temperature ◽

Nickel Base Superalloy ◽

Boundary Shear ◽

Room Temperature Ductility ◽

Solid Solution Matrix ◽

Nickel Base ◽

Solution Matrix ◽

Different Levels ◽

Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Download Full-text

ALCHEMI of B2-Ordered Fe50Al45Me5 alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100165203 ◽

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.

Download Full-text

GRAIN REFINEMENT AND MICROSTRUCTURE EVOLUTION IN ALUMINUM A2618 ALLOY BY HIGH-PRESSURE TORSION

Jurnal Teknologi ◽

10.11113/jt.v78.9163 ◽

2016 ◽

Vol 78 (6-9) ◽

Author(s):

Intan Fadhlina Mohamed ◽

Seungwon Lee ◽

Kaveh Edalati ◽

Zenji Horita ◽

Shahrum Abdullah ◽

...

Keyword(s):

Plastic Deformation ◽

High Pressure ◽

Grain Refinement ◽

Room Temperature ◽

Rotation Speed ◽

High Pressure Torsion ◽

Applied Pressure ◽

Saturation Level ◽

Microstructural Refinement ◽

Average Grain Size

This work presents a study related to the grain refinement of an aluminum A2618 alloy achieved by High-Pressure Torsion (HPT) known as a process of Severe Plastic Deformation (SPD). The HPT is conducted on disks of the alloy under an applied pressure of 6 GPa for 1 and 5 turns with a rotation speed of 1 rpm at room temperature. The HPT processing leads to microstructural refinement with an average grain size of ~250 nm at a saturation level after 5 turns. Gradual increases in hardness are observed from the beginning of straining up to a saturation level. This study thus suggests that hardening due to grain refinement is attained by the HPT processing of the A2618 alloy at room temperature.

Download Full-text

Mechanical properties of nickel beryllides

Journal of Materials Research ◽

10.1557/jmr.1989.1347 ◽

1989 ◽

Vol 4 (6) ◽

pp. 1347-1353 ◽

Cited By ~ 10

Author(s):

T. G. Nieh ◽

J. Wadsworth ◽

C. T. Liu

Keyword(s):

Crystal Structure ◽

Mechanical Properties ◽

Elastic Properties ◽

Room Temperature ◽

Vickers Microhardness ◽

Interstitial Oxygen ◽

Equiatomic Composition ◽

Room Temperature Ductility ◽

Hardness Increase ◽

Microhardness Tester

The elastic properties of nickel beryllide have been evaluated from room temperature to 1000 °C. The room temperature modulus is measured to be 186 GPa, which is relatively low by comparison with other B2 aluminides such as NiAl and CoAl. Hardness measurements were carried out on specimens that had compositions over the range from 49 to 54 at. % Be, using both a Vickers microhardness tester and a nanoindentor. It was found that the hardness of NiBe exhibits a minimum at the equiatomic composition. This behavior is similar to that of aluminides of the same crystal structure, e.g., NiAl and CoAl. The effect of interstitial oxygen on the hardness of NiBe has also been studied and the results show that the presence of oxygen in NiBe can cause a significant increase in hardness. It is demonstrated that the hardness increase for the off-stoichiometric compositions is primarily caused by interstitial oxygen and can only be attributed partially to anti-site defects generated in off-stoichiometric compositions. Nickel beryllides appear to have some intrinsic room temperature ductility, as evidenced by the absence of cracking near hardness indentations.

Download Full-text

Improvement of room temperature ductility for Mo and Fe modified Ti2AlNb alloy

Materials Science and Engineering A ◽

10.1016/j.msea.2010.09.003 ◽

2010 ◽

Vol 528 (1) ◽

pp. 355-362 ◽

Cited By ~ 32

Author(s):

Satoshi Emura ◽

Kaneaki Tsuzaki ◽

Koichi Tsuchiya

Keyword(s):

Room Temperature ◽

Room Temperature Ductility ◽

Ti2alnb Alloy

Download Full-text

Origin of enhanced room temperature ductility in TiAl alloys: Reducing activation difference of deformation mechanism of γ phase

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2021.163307 ◽

2021 ◽

pp. 163307

Author(s):

Ji Young Kim ◽

Eun Soo Park ◽

Taegu Lee ◽

Seunghwa Ryu ◽

Seung-Eon Kim ◽

...

Keyword(s):

Deformation Mechanism ◽

Room Temperature ◽

Tial Alloys ◽

Room Temperature Ductility

Download Full-text

Newly Developed Heat Resistant Magnesium Alloy by Thixomolding®

Materials Science Forum ◽

10.4028/www.scientific.net/msf.488-489.287 ◽

2005 ◽

Vol 488-489 ◽

pp. 287-290 ◽

Cited By ~ 1

Author(s):

Tadayoshi Tsukeda ◽

Ken Saito ◽

Mayumi Suzuki ◽

Junichi Koike ◽

Kouichi Maruyama

Keyword(s):

Aluminum Alloy ◽

Magnesium Alloy ◽

Magnesium Alloys ◽

Room Temperature ◽

Elevated Temperatures ◽

Die Casting ◽

The Other ◽

Heat Resistant ◽

Higher Temperature ◽

Better Than

We compared the newly developed heat resistant magnesium alloy with conventional ones by Thixomolding® and aluminum alloy by die casting. Tensile properties at elevated temperatures of AXEJ6310 were equal to those of ADC12. In particular, elongation tendency of AXEJ6310 at higher temperature was better than those of the other alloys. Creep resistance of AXEJ6310 was larger than that of AE42 by almost 3 orders and smaller than that of ADC12 by almost 2 orders of magnitude. Fatigue limits at room temperature and 423K of AXEJ6310 was superior among conventional magnesium alloys.

Download Full-text