Compression Studies on Particulate Composites of Ternary Al-Ti-Fe, and Quaternary Al-Ti-Fe-Nb and Al-Ti-Fe-Mn L12 Compounds

1990 ◽  
Vol 213 ◽  
Author(s):  
K.S. Kumar ◽  
M.S. Dipietro ◽  
J.D. Whittenberger
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
High Temperatures ◽  
Volume Fraction ◽  
Particulate Composites ◽  
Strain Rates ◽  
Warm Temperature ◽  
Monolithic Material ◽  
Alloying Additions ◽  
Before And After

ABSTRACTCompression studies were conducted on monolithic and TiB2 particulatereinforced composites of AI22 Fe3 Ti8, both with and without minor quaternary alloying additions (2 at.% Nb and 2 at.% Mn) as a function of temperature and as a function of strain rate at high temperature. The volume fraction of reinforcement was varied between 0 and 20 percent. The particulate reinforcements were found to be effective in increasing ambient- and warm-temperature strength; at high temperatures, the monolithic material is stronger than the composites, although the composites are superior at slow strain rates. The microstructures of the monolithic and composite specimens were examined before and after deformation to explain these observations.

Compression behavior of TiB2-particulate-reinforced composites of Al22Fe3Ti8

1991 ◽  
Vol 6 (3) ◽  
pp. 530-538 ◽  
Author(s):  
M.S. DiPietro ◽  
K.S. Kumar ◽  
J.D. Whittenberger
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Particulate Composites ◽  
Strain Rates ◽  
Monolithic Material ◽  
Compression Behavior ◽  
Dominant Deformation Mechanism ◽  
Compressive Flow ◽  
Particulate Reinforced Composites ◽  
Particulate Reinforced

The compression behavior of both the monolithic L12 compound Al22Fe3Ti8 and discontinuous composites obtained by incorporating ∼1 μm TiB2 particles was studied for various volume percent reinforcements as a function of temperature and at high temperatures as a function of strain rate. In this study, by varying the Fe and Ti contents, the nature and volume fraction of the minor phases coexisting with the dominant L12 phase were changed and were examined with and without TiB2 reinforcement. At high strain rates (10−4 s−1), the TiB2 reinforcements significantly enhance ambient and warm-temperature strength, although a crossover is observed at ∼1000 K, above which the monolithic material is stronger than the composite. At slow strain rates (10−7 s−1), representative of creep conditions, however, the TiB2-containing composites retain their superiority at least up to 1200 K. Power law fits of compressive flow stress at 1% strain versus strain rate yielded a stress exponent of ∼3.0 with an activation energy of 310 kJ/mol for the monolithic material. For the particulate composites (20 vol. % TiB2), the corresponding values were ∼5.0 and 465 kJ/mol, suggesting a change in the dominant deformation mechanism.

scholarly journals Alloys based on NiAl for High Temperature Applications

1984 ◽  
Vol 39 ◽  
Author(s):  
K. Vedula ◽  
V. Pathare ◽  
I. Aslanidis ◽  
R. H. Titran
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Powder Metallurgy ◽  
Flow Stress ◽  
High Temperatures ◽  
Strain Rates ◽  
Dislocation Interaction ◽  
Alloying Additions ◽  
Ternary Alloying ◽  
Temperature Applications

ABSTRACTThis paper presents some of the results obtained in an on-going study of NiAl alloys for potential high temperature applications. Alloys were prepared by powder metallurgy techniques. Flow stress values at slow strain rates and high temperatures were measured. Some promising ternary alloying additions (Hf, Ta and Nb) have been identified. The mechanism of strengthening in alloys containing these additions appears to be a form of particle dislocation interaction. Interesting effects of grain size and stoichiometry in binary alloys are also presented.

Stress-Strain Equations for Some Near-Eutectic Tin-Lead Solders

1991 ◽  
Vol 113 (4) ◽  
pp. 475-484 ◽  
Author(s):  
K. P. Jen ◽  
J. N. Majerus
Keyword(s):  
Strain Rate ◽  
Printed Circuit Boards ◽  
Volume Fraction ◽  
Total Error ◽  
Tensile Tests ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Strain Rates ◽  
Stress Strain ◽  
Engineering Strain

This paper presents the evaluation of the stress-strain behavior, as a function of strain-rate, for three tin-lead solders at room temperature. This behavior is critically needed for reliability analysis of printed circuit boards (PCB) since handbooks list minimal mechanical properties for the eutectic solder used in PCBs. Furthermore, most handbook data are for stable eutectic microstructure whereas PCB solder has a metastable microstructure. All three materials were purchased as “eutectics.” However, chemical analysis, volume fraction determination, and microhardness tests show some major variations between the three materials. Two of the materials have a eutectic composition, and one does not. The true stress-strain equations of one eutectic and the one noneutectic material are determined from compressive tests at engineering strain-rates between 0.0002/s and 0.2/s. The second eutectic material is evaluated using tensile tests with strain-rates between 0.00017/s and 0.042/s. The materials appear to exhibit linear elastic behavior only at extremely small strains, i.e., less than 0.0005. However, this “elastic” behavior showed considerable variation, and depended upon the strain rate. In both tension and compression the eutectic alloy exhibits nonlinear plastic behavior, i.e., strain-softening followed by strain-hardening, which depends upon the strain rate. A quadratic equation σy = σy(ε˚/ε˚0) + A(ε˚/ε˚0)ε + B(ε˚/ε˚0)ε2 fit to the data gives correlation coefficients R2 > 0.91. The coefficients σy(ε˚/ε˚0), A(ε˚/ε˚0), B(ε˚/ε˚0) are fitted functions of the normalized engineering strain rate ε˚/ε˚0. Replicated experiments are used at each strain-rate so that a measure of the statistical variation could be estimated. Measures of error associated with the regression analysis are also obtained so that an estimate of the total error in the stress-strain relations can be made.

High Temperature Deformation Mechanisms and Processing Map for Hot Working of Cast-Homogenized Mg-3Sn-2Ca Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 3616-3621 ◽  
Author(s):  
K.P. Rao ◽  
Y.V.R.K. Prasad ◽  
Norbert Hort ◽  
Karl Ulrich Kainer
Keyword(s):  
Strain Rate ◽  
Processing Map ◽  
Volume Fraction ◽  
Flow Instability ◽  
Back Stress ◽  
Hot Working ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Compression Tests

The hot working behavior of Mg-3Sn-2Ca alloy has been investigated in the temperature range 300–500 oC and strain rate range 0.0003–10 s-1, with a view to evaluate the mechanisms and optimum parameters of hot working. For this purpose, a processing map has been developed on the basis of the flow stress data obtained from compression tests. The stress-strain curves exhibited steady state behavior at strain rates lower than 0.01 s-1 and at temperatures higher than 350 oC and flow softening occurred at higher strain rates. The processing map exhibited two dynamic recrystallization domains in the temperature and strain rate ranges: (1) 300–420 oC and 0.0003–0.003 s-1, and (2) 420–500 oC and 0.003–1.0 s-1, the latter one being useful for commercial hot working. Kinetic analysis yielded apparent activation energy values of 161 and 175 kJ/mole in domains (1) and (2) respectively. These values are higher than that for self-diffusion in magnesium suggesting that the large volume fraction of intermetallic particles CaMgSn present in the matrix generates considerable back stress. The processing map reveals a wide regime of flow instability which gets reduced with increase in temperature or decrease in strain rate.

High Temperature Compression Properties of Ni3(Si,Ti) Based Intermetallic Compounds

2014 ◽  
Vol 783-786 ◽  
pp. 1129-1135
Author(s):  
Takehito Hagisawa ◽  
Hirokazu Madarame ◽  
Shinji Tanaka ◽  
Yasuyuki Kaneno ◽  
Takayuki Takasugi
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Strain Rate ◽  
Volume Fraction ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Ti Alloy ◽  
Compression Properties ◽  
Ti Alloys

High temperature compression properties of Al-, Cr-or Nb-added Ni3(Si,Ti) based intermetallic compounds were investigated by uni-axial compression test and microstructural observation. The Al-or Cr-added Ni3(Si,Ti) alloys after homogenization heat treatment exhibited a two-phase microstructure consisting of L12and Ni-solid solution phases. The Nb-added Ni3(Si,Ti) alloy after homogenization heat treatment exhibited a triple-phase microstructure consisting of G-phase with D8a structure and Ni-solid solution phase in the L12matrix. The volume fraction of Ni-solid solution phase increased in order of Cr-, Nb-and Al-added Ni3(Si,Ti) alloys. The Cr-added Ni3(Si,Ti) alloy was deformable at high strain rate, while the Nb-added one was deformable at low strain rate. It can be considered that the deformability of Ni3(Si,Ti) at high temperature is closely correlated with volume fraction of Ni-solid solution phase and recrystallization behavior.

Spark Plasma Sintering and Strength Behavior under Compressive Loading of Mg-PSZ/Al2O3-TRIP-Steel Composites

2015 ◽  
Vol 825-826 ◽  
pp. 182-188 ◽  
Author(s):  
Lutz Krüger ◽  
Steffen Grützner ◽  
Sabine Decker ◽  
Ines Schneider
Keyword(s):  
Strain Rate ◽  
Spark Plasma Sintering ◽  
Trip Steel ◽  
Volume Fraction ◽  
Compressive Yield Strength ◽  
Strain Rates ◽  
Steel Matrix ◽  
Trip Effect ◽  
Plasma Sintering ◽  
Spark Plasma

Composite materials, which consist of a metastable austenitic TRIP-steel matrix (CrMnNi TRIPsteel; TRansformation Induced Plasticity) reinforced by alumina particles (25 vol.% ceramic, designated as AT 25/75) and reinforced by alumina and MgO partially stabilized zirconia particles (Mg-PSZ) (35 vol.% ceramic, designated as AT 25/75 + MgPSZ) were synthesized through spark plasma sintering (SPS). In the AT 25/75 + MgPSZ, the steel particles were mainly surrounded by alumina. Hence, mostly steel/alumina and alumina/MgPSZ interfaces existed. The mechanical behavior of the as-sintered samples was characterized by compression tests at room temperature and 40 °C and in a range of strain rates between 103s-1and 103s1. The influence of the ceramic content, strain rate and temperature on TRIP-effect of the steel matrix was investigated. Due to the increasing ceramic volume fraction, AT 25/75 + MgPSZ exhibits the highest compressive yield strength under all loading conditions and no strain rate sensitivity. This composite showed no measurable TRIP-effect, due to the low fracture strain. The deformation-induced α’martensite within the steel particles in pure steel and AT 25/75 primary depends on the testing temperature and the strain rate. This is attributed to an increase of stacking fault energy with rising temperature. High strain rates cause adiabatic heating, counteracting the martensitic transformation.

Effect of Hot Deformation Parameters on Flow Behavior and Microstructure of Ti-6Al-4V-0.2O Alloy

2017 ◽  
Vol 898 ◽  
pp. 137-143
Author(s):  
Lin Xiang ◽  
Bin Tang ◽  
Hong Chao Kou ◽  
Jie Shao ◽  
Jin Shan Li
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Dynamic Recovery ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Height Reduction ◽  
Deformation Parameters

Isothermal compression tests were conducted to investigate the effect of hot deformation parameters on flow behavior and microstructure of Ti-6Al-4V-0.2O alloy. The experimental results show that the strain rate and height reduction have little effect on the volume fraction of primary α at a deformation temperature of 860 ̊C. At a deformation temperature of 940 ̊C, the volume fraction of primary α at a high strain rate (10s-1) is about 10% less than that at low strain rates (0.01s-1~1s-1). It may be one of the reasons for the significantly discontinuous yielding phenomenon. Another reason is that the dislocation density decreased suddenly due to the dynamic recovery. With the increasing strain rate and the decreasing deformation temperature, the volume fraction of irregular secondary α increases and lamellar secondary α decreases. And with height reduction increasing, the irregular secondary α increases firstly and then tends to be steady because of dynamic recovery and recrystallization.

Stability of TaC precipitates in a Co–Re-based alloy being developed for ultra-high-temperature applications

2016 ◽  
Vol 49 (4) ◽  
pp. 1253-1265 ◽  
Author(s):  
Ralph Gilles ◽  
Debashis Mukherji ◽  
Lukas Karge ◽  
Pavel Strunz ◽  
Premysl Beran ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Gas Turbines ◽  
Volume Fraction ◽  
Turbine Blades ◽  
Alloy Development ◽  
Carbide Phases ◽  
Ultra High Temperature ◽  
Temperature Applications

Co–Re alloys are being developed for ultra-high-temperature applications to supplement Ni-based superalloys in future gas turbines. The main goal of the alloy development is to increase the maximum service temperature of the alloy beyond 1473 K,i.e.at least 100 K more than the present single-crystal Ni-based superalloy turbine blades. Co–Re alloys are strengthened by carbide phases, particularly the monocarbide of Ta. The binary TaC phase is stable at very high temperatures, much greater than the melting temperature of superalloys and Co–Re alloys. However, its stability within the Co–Re–Cr system has never been studied systematically. In this study an alloy with the composition Co–17Re–23Cr–1.2Ta–2.6C was investigated using complementary methods of small-angle neutron scattering (SANS), scanning electron microscopy, X-ray diffraction and neutron diffraction. Samples heat treated externally and samples heatedin situduring diffraction experiments exhibited stable TaC precipitates at temperatures up to 1573 K. The size and volume fraction of fine TaC precipitates (up to 100 nm) were characterized at high temperatures within situSANS measurements. Moreover, SANS was used to monitor precipitate formation during cooling from high temperatures. When the alloy is heated the matrix undergoes an allotropic phase transformation from the ∊ phase (hexagonal close-packed) to the γ phase (face-centred cubic), and the influence on the strengthening TaC precipitates was also studied within situSANS. The results show that the TaC phase is stable and at these high temperatures the precipitates coarsen but still remain. This makes the TaC precipitates attractive and the Co–Re alloys a promising candidate for high-temperature application.

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