Effect of Interphase Boundary Character on Mechanical Properties in NiAl(β) Bicrystals with Ni 3Al(γ') Precipitates along Grain Boundary

2002 ◽  
Vol 753 ◽  
Author(s):  
Toshiya Sakata ◽  
Hiroyuki Y. Yasuda ◽  
Yukichi Umakoshi
Keyword(s):  
Mechanical Properties ◽  
Interphase Boundary ◽  
Fracture Stress ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Deviation Angle ◽  
Boundary Character ◽  
Temperature Fracture ◽  
Boundary Sliding

ABSTRACTRole of the crystallography of Ni 3Al(γ') precipitates along grain boundaries of NiAl(β) in the mechanical properties was systematically investigated using β bicrystals with controlled orientations. γ' phase preferentially precipitated along βgrain boundaries showing a film-like shape. The selected variant of γ'-film satisfied the Kurdjumov-Sachs (K-S) relation with a neighboring βcrystal but it deviated from the relation with another adjacent βcrystal. In the course of tensile deformation at room temperature, fracture occurred preferentially at incoherent (β/γ') interphase boundary deviating from the K-S relation and the fracture stress decreased with increasing deviation angle. In contrast, the interphase boundary sliding occurred preferentially at irrational (β/γ') interface at 1073K. The sliding displacement increased with increasing deviation angle. Thus, the mechanical properties of β bicrystals with γ'-film were found to depend strongly on the interphase boundary character.

scholarly journals Is Superplasticity in the Future of Nanophase Materials?

1990 ◽  
Vol 196 ◽  
Author(s):  
R. W. Siegel
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Grain Boundary Sliding ◽  
Atomic Clusters ◽  
Diffusional Creep ◽  
Ultrafine Grain ◽  
Grain Sizes ◽  
Nanophase Materials ◽  
Boundary Sliding

ABSTRACTThe ultrafine grain sizes and high diffusivities in nanophase materials assembled from atomic clusters suggest that these materials may have a strong tendency toward superplastic mechanical behavior. Both small grain size and enhanced diffusivity can be expected to lead to increased diffusional creep rates as well as to a significantly greater propensity for grain boundary sliding. Recent mechanical properties measurements at room temperature on nanophase Cu, Pd, and TiO2, however, give no indications of superplasticity. Nonetheless, significant ductility has been clearly demonstrated in these studies of both nanophase ceramics and metals. The synthesis of cluster-assembled nanophase materials is described and the salient features of what is known of their structure and mechanical properties is reviewed. Finally, the answer to the question posed in the title is addressed.

Superplasticity of Aerospace 7075 (Al-Zn-Mg-Cu) Aluminium Alloy Obtained by Severe Plastic Deformation

2018 ◽  
Vol 385 ◽  
pp. 39-44 ◽  
Author(s):  
Fernando Carreño ◽  
Oscar A. Ruano
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Aluminium Alloy ◽  
Room Temperature ◽  
Grain Boundary Sliding ◽  
Strain Rates ◽  
Aerospace Applications ◽  
Boundary Sliding ◽  
Processing Stress

The 7075 (Al-Zn-Mg-Cu) aluminium alloy is the reference alloy for aerospace applications due to its specific mechanical properties at room temperature, showing excellent tensile strength and sufficient ductility. Formability at high temperature can be improved by obtaining superplasticity as a result of fine, equiaxed and highly misoriented grains prone to deform by grain boundary sliding (GBS). Different severe plastic deformation (SPD) processing routes such as ECAP, ARB, HPT and FSP have been considered and their effect on mechanical properties, especially at intermediate to high temperatures, are studied. Refined grains as fine as 100 nm and average misorientations as high as 39o allow attainment of high strain rate superplasticity (HSRSP) at lower than usual temperatures (250-300oC). It is shown that increasing misorientations are obtained with increasing applied strain, and increasing grain refinement is obtained with increasing processing stress. Thus, increasing superplastic strains at higher strain rates, lower stresses and lower temperatures are obtained with increasing processing strain and, specially, processing stress.

Mechanical Behavior and Failure Mechanisms of SCS-6/Ti3Al Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
S. M. Jeng ◽  
C. J. Yang ◽  
J.-M. Yang ◽  
D. G. Rosenthal ◽  
J. Goebel
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Failure Mechanisms ◽  
Crack Initiation And Propagation ◽  
Al Composite ◽  
Initiation And Propagation ◽  
Bend Tests ◽  
Scanning Electron

AbstractThe mechanical properties and failure mechanisms of the SCS-6/Ti3Al composite have been studied. Both tensile and notched bend tests were conducted at room temperature on the monolithic and fiber-reinforced Ti-25Al-10Nb-3V-1Mo. Optical and scanning electron microscopy were used to study the crack initiation and propagation mechanisms. The role of the fiber, matrix and interfacial properties on the composite behavior was also assessed.

Effects of Rare Earth on the Inclusions and Mechanical Properties of Austenitic Stainless Steel

2013 ◽  
Vol 711 ◽  
pp. 99-102
Author(s):  
Xiao Liu ◽  
Jing Long Liang
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Rare Earth ◽  
Impact Toughness ◽  
Room Temperature ◽  
Transverse Impact ◽  
Dimple Fracture ◽  
Reduction Of Area ◽  
Room Temperature Strength

The effects of rare earth metals on the inclusions and the mechanical properties of 21Cr11Ni austenitic steel were studied by scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of inclusions in 21Cr11Ni stainless steel are changed, and rare earth played a very good role of modifying inclusions. The fracture mode of 21Cr11Ni stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding RE into the steel. The transverse impact toughness of 21Cr11Ni stainless steel is improved obviously by RE. In comparison with 21Cr11Ni stainless steel without RE, the transverse impact toughness of 21Cr11Ni stainless steel with RE is increased 25.33% at-40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 9.18%, 12.71% respectively.

Notch Effects on Room Temperature Tensile and Bend Properties of Ni3Al and Ni3Al+B

1988 ◽  
Vol 133 ◽  
Author(s):  
P. S. Khadkikar ◽  
J. D. Rigney ◽  
J. J. Lewandowski ◽  
K. Vedula
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Fracture Stress ◽  
Room Temperature ◽  
Tensile Tests ◽  
Boron Addition ◽  
Notched Specimens ◽  
Grain Boundary Fracture ◽  
Bend Tests ◽  
Boundary Fracture

ABSTRACTThe notched mechanical properties of Ni3AI and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Ten- sile tests performed using double notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3AI+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

Effect of Nitrogen on the Mechanical Properties of Heat-Resisting Steel

2012 ◽  
Vol 535-537 ◽  
pp. 571-575
Author(s):  
Xiao Liu ◽  
Long Mei Wang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Room Temperature ◽  
Rupture Strength ◽  
N Addition ◽  
Creep Rupture Strength ◽  
Test Steel ◽  
Scanning Electron

In this paper, the effect of N addition on mechanical properties of 21Cr-11Ni austenitic heat-resisting stainless steel was investigated. Scanning electron microscopy was used to study the fracture surfaces in the steels. N in 21Cr–11Ni heat-resisting steel can play a role of stabling austenite and ensuring the structure and mechanical properties in high temperatures. Fracture is changed from cleavage to ductile fracture to 21Cr–11Ni heat-resisting steel, and the strength of test steel are improved at room temperature by adding N, the tensile strength is increased by 8.33%. And the creep rupture strength is improved. The fracture time of the steel containing 0.2% N is 3.2 times higher than the steel containing 0.14% N at 1144K.

The Role of Dislocations in the Superplastic Deformation of a Duplex Stainless Steel

1990 ◽  
Vol 196 ◽  
Author(s):  
T. R. Parayil ◽  
G. L. Dunlop ◽  
P. R. Howell
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Interphase Boundary ◽  
Superplastic Deformation ◽  
Transmission Electron ◽  
Dislocation Arrays ◽  
Boundary Sliding ◽  
Region Ii ◽  
Dislocation Multiplication

ABSTRACTTransmission electron microscopy (TEM) has been employed to examine the role of dislocations in the superplastic deformation of a duplex stainless steel. In particular, matrix, grain boundary and interphase interface dislocation distributions have been documented after testing in region II. It is concluded that dislocation activity is of importance during superplastic flow and both loop sources and dislocation pile-ups have been observed. The presence of highly distorted dislocation arrays also suggests that grain and interphase boundary sliding is intimately linked to the motion of grain and interphase boundary dislocations. Finally, it is argued that dislocation multiplication in interphase interfaces can involve the operation of loop sources.

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.

Effect of Trace Ce and B Additions on the Mechanical Properties of Nb-3Si-22Ti Alloys

2017 ◽  
Vol 898 ◽  
pp. 454-460
Author(s):  
Mei Ling Wu ◽  
Feng Wei Guo ◽  
Ming Li ◽  
Yong Wang Kang ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Room Temperature ◽  
Arc Melting ◽  
Trace Addition ◽  
B Additions ◽  
Temperature Fracture ◽  
Ultrahigh Temperature ◽  
The Relationship

The Nb-Si system ultrahigh temperature alloys were prepared by vacuum non-consumable arc melting. The influence of micro-alloying elements of B and Ce on the hardness, room-temperature fracture toughness and compressive strength at 1250°C of the Nb-22Ti-3Si alloys was investigated and estimated systematically. The results showed that the hardness of the Nb-22Ti-3Si alloy increased obviously with trace B addition, but decreased slightly with trace Ce addition. The room-temperature fracture toughness of the Nb-22Ti-3Si alloy was degraded by the Ce addition but improved by the trace addition of B. The trace addition of B improved the compressive strength of the alloy at 1250°C. In contrast, the trace Ce addition degraded the compressive strength at 1250°C. The relationship between the microstructure and the mechanical properties was discussed.

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