Influence of Ni Addition on Mechanical Properties and Fracture Behaviors of Ir-15Nb Two-Phase Refractory Superalloys

1998 ◽  
Vol 552 ◽  
Author(s):  
Yuefeng Gu ◽  
Y. Yamabe-Mitarai ◽  
Y. Ro ◽  
T. Yokokawa ◽  
H. Harada
Keyword(s):  
Mechanical Properties ◽  
Intergranular Fracture ◽  
Coherent Structure ◽  
Room Temperature ◽  
Two Phase ◽  
Ni Content ◽  
Ni Addition ◽  
Fracture Behaviors ◽  
Materials Used ◽  
Brittle Intergranular Fracture

ABSTRACTIr-based alloys with fcc-L12 two-phase coherent structure, which are called “refractory superalloys”, have good potentiality as structure materials used at ultra-high temperatures up to 2000 °C. Preliminary results showed that the refractory superalloys failed predominately by brittle intergranular fracture at room temperature even though they showed higher strength at that temperature. This paper will present the influence of nickel (Ni) addition on mechanical properties and fracture behaviors of one of these alloys, Ir-15at%Nb. The results indicated that Ni addition was beneficial to the compression ductility and strength of two-phase Ir-15at%Nb alloy when Ni content was below the optimum content.

Influence of hardening additives on the characteristics of TiC‒Al2O3 ceramic composite tribological applications, obtained by SHS

2020 ◽  
pp. 47-55
Author(s):  
D. H. A. Besisa ◽  
Z. I. Zaki ◽  
A. M. M. Amin ◽  
Y. M. Z. Ahmed ◽  
E. M. M. Ewais
Keyword(s):  
Mechanical Properties ◽  
Ceramic Composite ◽  
Densification Behavior ◽  
Nickel Metal ◽  
Temperature Synthesis ◽  
Ni Content ◽  
Microstructure And Mechanical Properties ◽  
High Temperature Synthesis ◽  
Ni Addition ◽  
Different Content

In attempts to attain a SHS synthesized TiC‒Al2O3 composite with high density, homogenous microstructure and extra mechanical properties for using in aggressive media, addition of different reinforcements have to be studied and inspected. In this work, ductile nickel metal powder with different content (5‒20 wt. %) and 1 mole fraction dilution of alumina and zirconia with and without Ni addition are introduced to TiC‒Al2O3 ceramic and synthesized by combined self-propagating high temperature synthesis (SHS) and direct consolidation (DC) technique. The influence of nickel wt. % and dilution with zirconia and alumina on the phase composition, densification behavior, microstructure and mechanical properties of SHS synthesized TiC‒Al2O3 composite has been investigated and analyzed. Results revealed that, addition of 5 wt. % Ni gave the best densification behavior, microstructure and mechanical properties with exact formation of the target composite of TiC‒Al2O3. However, increasing Ni content higher than 5 wt % and dilution with zirconia and alumina led to disturbing the chemical reactions between the starting precursors, drooping and deterioration in density, microstructure and mechanical properties. Accordingly, this study suggests the addition of 5 wt. % Ni for a highly dense TiC‒Al2O3 composite with homogenized morphology and unparalleled mechanical properties. Moreover, the different investigated characteristics of the produced composites nominate it strongly to be used successfully in aggressive and tribological applications.

scholarly journals Key Microstructures Controlling the Mechanical Properties of Two-Phase TiAl Alloys with Lamellar Structures

1996 ◽  
Vol 460 ◽  
Author(s):  
C. T. Liu ◽  
P. J. Maziasz ◽  
J. L. Wright
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Elongation ◽  
Interlamellar Spacing ◽  
Hot Extrusion ◽  
Two Phase ◽  
Tial Alloys ◽  
Lamellar Structures

ABSTRACTThe objective of this study is to identify key microstructural parameters which control the mechanical properties of two-phase γ-TiAl alloys with lamellar structures. TiAl alloys with the base composition of Ti-47Al-2Cr-2Nb (at. %) were prepared by arc melting and drop casting, followed by hot extrusion at temperatures above the oc-transus temperature, Tα. The hot extruded materials were then heat treated at various temperatures above and below Tα in order to control microstructural features in these lamellar structures. The mechanical properties of these alloys were determined by tensile testing at temperatures to 1000° C. The tensile elongation at room temperature is strongly dependent on grain size, showing an increase in ductility with decreasing grain size. The strength at room and elevated temperatures is sensitive to interlamellar spacing, showing an increase in strength with decreasing lamellar spacing. Hall-Petch relationships hold well for the yield strength at room and elevated temperatures and for the tensile elongation at room temperature. Tensile elongations of about 5% and yield strengths around 900 MPa are achieved by controlling both colony size and interlamellar spacing. The mechanical properties of the TiAl alloys with controlled lamellar structures produced directly by hot extrusion are much superior to those produced by conventional thermomechanical treatments.

Microstructure and Properties of Ti-47Al-2W-0.5Si Cast Alloy

2015 ◽  
Vol 226 ◽  
pp. 3-6
Author(s):  
Agnieszka Szkliniarz ◽  
Wojciech Szkliniarz
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Room Temperature ◽  
Induction Furnace ◽  
Cast Alloy ◽  
Operating Conditions ◽  
Vacuum Induction Furnace ◽  
Two Phase ◽  
Microstructure And Properties

The paper characterized the phase composition, microstructure and selected mechanical properties at room temperature and at temperature corresponding to the expected operating conditions of two-phase Ti-47Al-2W-0.5Si cast alloy melted in a vacuum induction furnace in a special graphite crucibles.

Microstructure and Mechanical Properties of a Novel Ti-6.5Al-2Sn-4Zr-1.5Mo-2Nb-0.25Fe-0.2Si High-Temperature Titanium Alloy

2020 ◽  
Vol 993 ◽  
pp. 351-357
Author(s):  
Ming Yu Zhao ◽  
Xiao Yun Song ◽  
Wen Jing Zhang ◽  
Yu Wei Diao ◽  
Wen Jun Ye ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Room Temperature ◽  
Annealing Treatment ◽  
Tensile Tests ◽  
Electron Backscattered Diffraction ◽  
Two Phase ◽  
Bimodal Structure ◽  
Α Phase ◽  
Microstructure And Mechanical Properties

The Ti-6.5Al-2Sn-4Zr-1.5Mo-2Nb-0.25Fe-0.2Si (wt%) alloy is a novel two-phase high temperature alloy for short-term application. The effects of different heat treatments on the microstructure and mechanical properties were investigated through electron probe microanalysis (EPMA), optical microcopy (OM), scanning electron microscope (SEM), electron backscattered diffraction (EBSD) and tensile tests at room temperature and 650°C. Subjected to the annealing treatment at α+β region (1010 °C/2 h, FC to 990 °C+990 °C/2 h, AC), the microstructure was composed of bimodal structure, which consists of equiaxed primary α (αp) phase and lamellar transformed β (βt) structure. As a strong β stabilizer, the content of Fe in α phase is much less than that in β phase. Annealing at β region (1040 °C/2 h, AC) resulted in the formation of widmannstatten structure, consisting of coarse raw β grain and secondary α phase precipitated on the β grain. With respect to the tensile property, different heat-treated alloys obtained similar strength. However, widmannstatten structure was characterized by lower plasticity, with the elongation only half that of bimodal structure. The fracture characteristics at room temperature for the alloy with bimodal structure and widmannstatten structure are dominated by ductile fracture and cleavage fracture, respectively.

Microstructures and Mechanical Properties of NiAl+Mo In-Situ Eutectic Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
P. R. Subramanian ◽  
M. G. Mendiratta ◽  
D. B. Miracle ◽  
D. M. Dimiduk
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Room Temperature ◽  
Composite System ◽  
Elevated Temperatures ◽  
Two Phase ◽  
Structural Applications ◽  
Temperature Fracture

AbstractThe quasibinary NiAI-Mo system exhibits a large two-phase field between NiAl and the terminal (Mo) solid solution, and offers the potential for producing in-situ eutectic composites for high-temperature structural applications. The phase stability of this composite system was experimentally evaluated, following long-term exposures at elevated temperatures. Bend strengths as a function of temperature and room-temperature fracture toughness data are presented for selected NiA1-Mo alloys, together with results from fractography observations.

Microstructures and Mechanical Properties of Two-Phase FeNiMnAl Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 2549-2554 ◽  
Author(s):  
Ian Baker ◽  
Xiao Lan Wu ◽  
Fan Ling Meng ◽  
Paul R. Munroe
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Temperature Dependence ◽  
Room Temperature ◽  
High Strength ◽  
Two Phase ◽  
Nanostructured Alloys ◽  
Microstructures And Mechanical Properties ◽  
Very High

This paper presents an overview of the microstructures found in a range of two-phase FeNiMnAl alloys ranging from near-equiatomic very high-strength nanostructured alloys, such Fe30Ni20Mn25Al25, to more ductile f.c.c./B2 alloys, such as Fe30Ni20Mn35Al15. The effect of annealing at 823 K on the room temperature hardness is presented together with the temperature dependence of the yield strength.

Microstructures and mechanical properties of NiAl–Ni2AlHf alloys

1990 ◽  
Vol 5 (6) ◽  
pp. 1189-1196 ◽  
Author(s):  
M. Takeyama ◽  
C. T. Liu
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
High Hardness ◽  
Lattice Misfit ◽  
Two Phase ◽  
Heusler Phase ◽  
Thermally Activated ◽  
Rapid Drop ◽  
Very High

The microstructure and mechanical properties of several Ni–Al–Hf alloys in the composition range between NiAl (β) and Ni2AlHf (Heusler phase) have been studied. The volume fraction of Heusler phase, Vf, in these alloys varies from about 15 to 96%. The lattice misfit between the β and Heusler phases in two-phase alloys is larger than 5%, indicating no coherency between them. The yield strength increases with increasing Vf at all temperatures to 1000°C. Compressive ductilities of 4 and 7% were obtained for the alloy with Vf of 15% at room temperature and 500°C, respectively, but they decreased to 0% with increasing Vf to 96%. The corresponding fracture mode is basically transgranular cleavage. However, all the alloys can be deformed extensively without fracture at 1000°C. The hardness of the Heusler alloy is very high (8.3 GPa) at room temperature, and it decreases gently with temperature to 600°C, followed by a rapid decrease to 1000°C. The brittleness and high hardness of the Ni2AlHf Heusler phase at low temperatures are interpreted in terms of internal lattice distortion resulting from its crystal structure. The thermally activated process of deformation takes place above 600°C, which is responsible for the rapid drop of the hardness of the alloys.

scholarly journals Improving of Mechanical Properties of Titanium Alloy VT23 due to Impact-Oscillatory Loading and the Use of Carbon Nano-Solution

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 652
Author(s):  
Mykola Chausov ◽  
Oleg Khyzhun ◽  
Janette Brezinová ◽  
Pavlo Maruschak ◽  
Andrii Pylypenko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Titanium Alloy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
High Strength ◽  
Surface Layers ◽  
Two Phase ◽  
X Ray ◽  
Alloy Vt23

Improvement in the mechanical properties of sheet two-phase high-strength titanium alloy VT23 due to impact-oscillatory loading and the use of carbon nanosolutions at room temperature was tested experimentally. It was shown that in addition to obtaining a significant increase in the initial plastic deformation of the alloy, it is possible to strengthen the surface layers of the alloy by a factor of 8.4% at a time via the impulse introduction of energy into the alloy and the use of carbon nanosolutions. Using X-ray photoelectron spectroscopy (XPS), it was first found that strengthening of the surface layers of the titanium alloy at a given load, in line with using a carbon nanosolution, leads to the formation of a mixture of titanium oxide and titanium carbide or oxycarbide of type TiO2−xCx on the surface.

scholarly journals Effect of Si and Ni Addition on Graphite Morphology in Heavy-Section Spheroidal Graphite Iron Parts

2018 ◽  
Vol 925 ◽  
pp. 70-77 ◽  
Author(s):  
Branko Bauer ◽  
Ivana Mihalic Pokopec ◽  
Mitja Petrič ◽  
Primož Mrvar
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Metallographic Analysis ◽  
Spheroidal Graphite ◽  
Ni Content ◽  
Heavy Section ◽  
Graphite Morphology ◽  
Ni Addition ◽  
Chunky Graphite ◽  
Si Content

Metallographic analysis is applied to the study of the chunky graphite morphology in heavy-section castings of spheroidal graphite cast irons. Three castings with different Si and Ni content were prepared. Three positions in casting from the edge to the centre, with different cooling rates, were chosen for microstructure observation. The effect of the Si and Ni content on the graphite morphology and mechanical properties of heavy-section spheroidal graphite cast iron parts were investigated. Cerium containing commercial inoculant was used for in-stream inoculation. Chunky graphite area was estimated in micro-and macrostructure. Mechanical properties were determined on tensile test bars taken from the centre of the casting. Macro-and microstructure examination showed that the castings with high Si-content and Ni addition had chunky graphite present, while the castings produced by use of low Si and Ni containing charge had no chunky graphite. High Si-content is strong chunky graphite promoter, especially in castings with slow cooling rate. Ni addition also promotes chunky graphite formation, but only in thermal centre of the casting (where the cooling rate is the lowest). The elongation is severely lowered when chunky graphite appears in the microstructure.

The Effect of Mixed RE Elements on Microstructure and Mechanical Properties of Die-Cast AZ91D Alloy

2014 ◽  
Vol 941-944 ◽  
pp. 59-65
Author(s):  
Jia Wei Yuan ◽  
Xing Gang Li ◽  
Kui Zhang ◽  
Yong Jun Li ◽  
Ming Long Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Properties ◽  
Room Temperature ◽  
Az91d Alloy ◽  
Microstructure And Mechanical Properties ◽  
Die Cast ◽  
Fracture Behaviors ◽  
Re Elements

The effect of mixed RE elements (Y, Nd, Gd ) on the microstructure and tensile properties of die-cast AZ91D alloy were investigated. The results indicated that the content of mixed RE elements lead to the change of the formation of Al▔RE compounds and reduction of the fraction of β-Mg17Al12 phase. The grain size of the alloy added 1.0wt. % RE became smaller than die-cast AZ91D and AZ91D+2.0wt. % RE alloys. The UTS of die-cast AZ91D+xRE(x=0 wt. %, 1.0wt. %, 2.0 wt. %) alloys were 204MPa, 194MPa, 203.6MPa at room temperature, respectively. Moreover, RE addition resulted in fracture behaviors changed.

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