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.

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.

The Influence of Carbon Addition on Microstructure and Mechanical Properties of Fe-22.0Al-5.0Ti Alloy

2014 ◽  
Vol 1043 ◽  
pp. 17-21 ◽  
Author(s):  
Ravi Kant ◽  
Ashish Selokar ◽  
Vijaya Agarwala ◽  
U. Prakash
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
High Hardness ◽  
Low Carbon ◽  
Carbon Addition ◽  
Two Phase ◽  
Solid Solution Strengthening ◽  
Load Carrying ◽  
Solution Strengthening

The effect of carbon addition on Fe-22.0Al-5.0Ti alloy on structure and properties has been investigated. Microstructural and phase analysis have been investigated by using optical microscopy, scanning electron microscope (SEM) equipped with EDAX. For low carbon addition (0.1 wt.%), two-phase microstructure consisting of precipitates of TiC in B2 matrix. The presence of large amount of carbon (1.0 or 1.5 wt.%) resulted formation of Fe3AlC0.5 and TiC precipitates in B2 matrix. The results show that the mechanical properties of Fe-22.0Al-5.0Ti increased with increase in the carbon content and strongly depend upon nature and volume fraction of different precipitates. The volume fraction of precipitates increased with increase in the content of carbon. The behavior of Fe-22.0Al-5.0Ti alloy was explained by the combined effect of precipitation hardening and solid solution strengthening. The main effect of addition of carbon related to improvement in the compressive strength without loss in the ductility. The decrease in the wear rate is mainly attributed to the high hardness of the composites and as well hard TiC play a role of load carrying.

scholarly journals Effect of Reverse-phase Transformation Annealing Process on Microstructure and Mechanical Properties of Medium Manganese Steel

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1633 ◽  
Author(s):  
Yan Zhao ◽  
Lifeng Fan ◽  
Bin Lu
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Volume Fraction ◽  
Lath Martensite ◽  
Phase Region ◽  
Manganese Steel ◽  
Reverse Phase ◽  
Two Phase ◽  
Fine Grain ◽  
Martensite Microstructure

In order to develop a third-generation automobile steel with powerful strength and elongation, we propose a method through high temperature quenching and two-phase region reverse-phase transformation annealing to develop such steel with 0.13% C and 5.4% Mn. To investigate the microstructure evolution and mechanical properties of manganese steel, SEM, XRD and TEM are employed in our experiments. Experimental results indicate that the microstructure after quenching is mainly lath martensite microstructure with average of lath width at 0.5 μm. The components of the steel after along with reverse-phase transformation annealing are ultra-fine grain ferrite, lath martensite and different forms of austenite microstructure. When the temperature at 625 °C, the components of the steel mainly includes lath martensite microstructure and ultra-fine grain ferrite and the fraction of austenite volume is only 5.09%. When the annealing temperature of reverse-phase transformation increase into 650 °C and 675 °C, the austenite appears in the boundary of the ferritic grain boundary and the boundary of lath martensite as the forms of bulk and lath. The phenomenon appears in the bulk of austenite, and the size of is 0.22 μm, 0.3 μm. The fraction of austenite volume is 22.34% at 675 °C and decreases into 9.32% at 700 °C. The components of austenite mainly includes ultra-fine grained ferrite and lath martensite. Furthermore, the density of decreases significantly, and the width of martensite increases into 0.32 μm. In such experimental settings, quenching at 930 °C with 20 min and at 675 °C with 30 min reverse-phase transformation annealing, the austenite volume fraction raises up to 22.34%.

Effect of rolling deformation on microstructure and mechanical properties of 2205 duplex stainless steel with micro-nano structure

2020 ◽  
Vol 34 (25) ◽  
pp. 2050269
Author(s):  
Yuqi Mao ◽  
Yuehong Zheng ◽  
Yu Shi ◽  
Min Zhu ◽  
Saitejin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Volume Fraction ◽  
Two Phase ◽  
Corrosion Properties ◽  
Nano Structure ◽  
2205 Duplex Stainless Steel ◽  
Microstructure And Mechanical Properties ◽  
Rolling Deformation

In order to further expand the application scope of 2205 duplex stainless steel (DSS), its microstructure and mechanical properties require as much attention as its corrosion properties. In this study, 2205DSSs were prepared by aluminothermic reaction and the microstructures and mechanical behavior of the rolled alloys were analyzed. The micro-nanocrystals composite structure appears in the alloys after rough rolling with deformation of 40% at [Formula: see text]C followed by finishing rolling with deformation of 30%, 50% and 70% at [Formula: see text]C. With the increase of rolling deformation, the two-phase structure is gradually elongated, the average size of the two-phase grains is gradually increased, and some [Formula: see text] phase will change to [Formula: see text] phase, the volume fraction of [Formula: see text] phase is gradually increased, and the distribution of nanocrystals is gradually uniform. Meanwhile, the fracture mode of alloy is gradually changed from ductile fracture to brittle fracture. The strength and hardness of the alloy increase gradually.

Fabrication and investigation on the properties of ilmenite (FeTiO3)-based Al composite by accumulative roll bonding

2019 ◽  
Vol 54 (10) ◽  
pp. 1259-1271 ◽  
Author(s):  
Medhat Elwan ◽  
A Fathy ◽  
A Wagih ◽  
A R S Essa ◽  
A Abu-Oqail ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Accumulative Roll Bonding ◽  
Room Temperature ◽  
Volume Fraction ◽  
Raw Material ◽  
Accumulative Roll Bonding Process ◽  
Roll Bonding ◽  
Hardness Tests ◽  
Al Composite

In the present study, the aluminum (Al) 1050–FeTiO3 composite was fabricated through accumulative roll bonding process, and the resultant mechanical properties were evaluated at different deformation cycles at ambient temperature. The effect of the addition of FeTiO3 particle on the microstructural evolution and mechanical properties of the composite during accumulative roll bonding was investigated. The Al–2, 4, and 8 vol.% FeTiO3 composites were produced by accumulative roll bonding at room temperature. The results showed improvement in the dispersions of the particles with the increase in the number of the rolling cycles. In order to study the mechanical properties, tensile and hardness tests were applied. It was observed that hardness and tensile strength improve with increasing accumulative roll bonding cycles. The microhardness and tensile strength of the final composites are significantly improved as compared to those of original raw material Al 1050 and increase with increasing volume fraction of FeTiO3, reaching a maximum of ∼75 HV and ∼169 MPa for Al–8 vol.% FeTiO3 at seventh cycle, respectively.

Influence of Speed of Processing in the Mechanical and Thermomechanical Properties of Polyamide 6 / Organoclay Nanocomposite

2014 ◽  
Vol 775-776 ◽  
pp. 383-387 ◽  
Author(s):  
Renê Anísio da Paz ◽  
E.M. Araújo ◽  
L.A. Pessan ◽  
T.J.A. Melo ◽  
A.M.D. Leite ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polymer Matrix ◽  
Volume Fraction ◽  
Bentonite Clay ◽  
Polyamide 6 ◽  
Thermomechanical Properties ◽  
High Ratio ◽  
Organic Salts ◽  
Load Volume ◽  
Very High

The improvement in the properties of nanocomposites is achieved with a load volume fraction of up to 10% due to the very high ratio of the load aspect. Moreover, they have the advantage of being processed with conventional equipment and techniques (extrusion, injection, etc.) used for polymers. In order for the clay to be uniformly dispersed in the polymer and there to be good interaction with the polymer matrix, superficial treatments of the clays with organic salts are essential for it to become organophilic, and, thus the material obtained has better performance. In this study, it was evaluated the influence of two speeds (100 and 200 rpm) of processing and thermo mechanical properties of nanocomposites with 3% of bentonite clay prepared with two speeds and two threads. The nanocomposites showed better properties as compared to properties of polyamide 6, especially the samples heated at screw speed of 100 rpm.

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.

Influence of the Ageing Temperature on the Selected Mechanical Properties of the Ti6Al7Nb Alloy

2015 ◽  
Vol 641 ◽  
pp. 120-123 ◽  
Author(s):  
Robert Dąbrowski ◽  
Janusz Krawczyk ◽  
Edyta Rożniata
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Volume Fraction ◽  
Heating Temperature ◽  
Ageing Temperature ◽  
Sample Length ◽  
Two Phase ◽  
Β Phase ◽  
Α Phase ◽  
The Impact

The results of investigations of the influence of the ageing temperature on the selected mechanical properties i.e. hardness, fracture toughness (examined by the linear elastic fracture mechanics - KIctest) and impact strength (KV) of two-phase Ti6Al7Nb alloy, are presented in the hereby paper. Investigations were performed in the ageing temperatures range: 450÷650°C of the alloy previously undercooled from the selected heating temperature (in two-phase range) - equal 970°C. The heating temperature was determined on the basis of the dilatometric curve of the alloy heating in the system ΔL = f ((T), where: ΔL – change of the sample length, T – temperature, which was then differentiated in the system: ΔL/ΔT = f (T). The dilatometer L78 R.I.T.A of the LINSEIS Company was used in the tests. Investigations of the alloy microstructure in the ageing temperatures range 450÷650°C were carried out by means of the light microscope Axiovert 200 MAT of the Carl Zeiss Company. It was found that nearly equiaxial grains of the primary α phase occur in the microstructure (of the volume fraction app. 30%) and that the volume fraction of the new lamellar α phase - formed from the supersaturated β phase - increases. With an increase of the alloy ageing temperature, in the mentioned above range, a small increase of its hardness from 305 to 324HV as well as a decrease of stress intensity factor KIcfrom 67.3 to 48.6 MPa x m1/2and impact strength (KV) from 40.2 to 31.3 J. The impact tests results were supplemented by the fractographic documentation. It was found, that the characteristic features of the fractures of impact test samples do not exhibit essential differences in dependence of the ageing temperature and material hardness. The fractographic investigations were performed by means of the scanning electron microscope NovaNanoSEM 450.

scholarly journals Effect of Rolling Temperature on Microstructure Evolution and Mechanical Properties of AISI316LN Austenitic Stainless Steel

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1557 ◽  
Author(s):  
Yi Xiong ◽  
Yun Yue ◽  
Tiantian He ◽  
Yan Lu ◽  
Fengzhang Ren ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Volume Fraction ◽  
Parent Phase ◽  
Rolling Temperature ◽  
Tensile Fracture ◽  
Transformation Rate

The impacts of rolling temperature on phase transformations and mechanical properties were investigated for AISI 316LN austenitic stainless steel subjected to rolling at cryogenic and room temperatures. The microstructure evolution and the mechanical properties were investigated by means of optical, scanning, and transmission electron microscopy, an X-ray diffractometer, microhardness tester, and tensile testing system. Results showed that strain-induced martensitic transformation occurred at both deformation temperatures, and the martensite volume fraction increased with the deformation. Compared with room temperature rolling, cryorolling substantially enhanced the martensite transformation rate. At 50% deformation, it yielded the same fraction as the room temperature counterpart at 90% strain, while at 70%, it totally transformed the austenite to martensite. The strength and hardness of the stainless steel increased remarkably with the deformation, but the corresponding elongation decreased dramatically. Meanwhile, the tensile fracture morphology changed from a typical ductile rupture to a mixture of ductile and quasi-cleavage fracture. The phase transformation and deformation mechanisms differed at two temperatures, with the martensite deformation contributing to the former, and austenite deformation to the latter. Orientations between the transformed martensite and its parent phase followed the K–S (Kurdjumov–Sachs) relationship.

On Crystallographic Texture of As-Drawn Doped-W Wires

2005 ◽  
Vol 495-497 ◽  
pp. 913-918 ◽  
Author(s):  
S.K. Yerra ◽  
Bert Verlinden ◽  
Paul van Houtte
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behaviour ◽  
Crystallographic Texture ◽  
Deformation Zone ◽  
Room Temperature ◽  
Volume Fraction ◽  
Wire Diameter ◽  
Texture Characteristics ◽  
The Wire ◽  
Textural Changes

Industrially processed doped-tungsten wires in the as-drawn condition have essentially a <110>-fibre texture with attractive mechanical properties. The main objectives of the present work are to investigate (I) if any textural changes occur as the wire diameter decreases and (II) if such changes influence the mechanical behaviour of the wire. A wire of about ∅1.5mm is drawn to about ∅0.15mm following a standard industrial route and samples were collected from five intermediate drawing passes. Bulk texture measurements using X-radiations were then carried on the transverse sections of the wires and texture characteristics such as volume fraction of textural components and sharpness index were quantified with respect to the wire diameter. It was observed that the texture in the as-drawn wires remains chiefly the same <110>-fibre as the wire diameter decreases. However, the sharpness of texture reaches a maximum at a certain diameter and decreases with further decrease in the wire diameter. An explanation is offered based on the concept of deformation zone geometry. An attempt was also made to determine if texture weakening has any effect on the mechanical properties of the wire at room temperature.

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