scholarly journals Effect of Zn and Ca Addition on Microstructure and Strength at Room Temperature of As-Cast and As-Extruded Mg-Sn Alloys

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1490 ◽  
Author(s):  
Yang Zhang ◽  
Leipeng Song ◽  
Xiaoyang Chen ◽  
Yalin Lu ◽  
Xiaoping Li
Keyword(s):  
Dynamic Recrystallization ◽  
Room Temperature ◽  
Volume Fraction ◽  
Hot Extrusion ◽  
Fiber Texture ◽  
Ca Addition ◽  
The Matrix ◽  
Mg2sn Phase

In this study, the effect of Zn and Ca addition on microstructure and strength at room temperature of Mg-Sn alloys was investigated by comparison of Mg-6Sn, Mg-6Sn-2Zn, and Mg-6Sn-2Zn-1Ca alloys in as-cast and as-extruded states. In the as-cast samples, α-Mg and Mg2Sn phases were the main phases of Mg-6Sn and Mg-6Sn-2Zn alloys, while the CaMgSn phase was formed in Mg-6Sn-2Zn-1Ca alloy due to the addition of the Ca element. Mg2Sn phase dissolved into the matrix during homogenization while CaMgSn phase remained. Incomplete dynamic recrystallization (DRX) took place in these alloys during hot extrusion. Fine Mg2Sn precipitates were observed in α-Mg matrix of as-extruded samples. Zn showed little influence on microstructure, whereas Ca reduced the volume fraction of un-DRXed grains and increased the size of DRXed grains. As-extruded Mg-Sn alloys exhibited typical fiber texture. The strength at room temperature of Mg-Sn alloys improved significantly after hot extrusion. The addition of Zn element was beneficial to the strength at room temperature of the Mg-6Sn alloy, while the further addition of Ca element was harmful to the strength. Among these alloys, the Mg-6Sn-2Zn alloy exhibited the best strength at room temperature in both as-cast and as-extruded states.

Characristics of Shape Memory Composites Combined with Shape Memory Alloy and Shape Memory Polymer

2013 ◽  
Vol 705 ◽  
pp. 169-172
Author(s):  
Xue Feng ◽  
Li Min Zhao ◽  
Xu Jun Mi
Keyword(s):  
Shape Memory ◽  
Room Temperature ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Young Modulus ◽  
Thermomechanical Properties ◽  
The Matrix ◽  
Shape Memory Composites ◽  
Shape Fixity

In order to develop high functionality of shape memory materials, the shape memory composites combined with TiNi wire and shape memory epoxy were prepared, and the mechanical and thermomechanical properties were studied. The results showed the addition of TiNi wire increased the Young modulus and breaking strength both at room temperature and at elevated temperature. The composites maintained the rates of shape fixity and shape recovery close to 100%. The maximum recovery stress increased with increasing TiNi wire volume fraction, and obtained almost 3 times of the matrix by adding 1vol% TiNi wire.

scholarly journals Multi-scale reinforcements stimulated dynamic recrystallization and mechanical behavior of as-extruded titanium matrix composites

2020 ◽  
Vol 321 ◽  
pp. 08005
Author(s):  
Peikun Qiu ◽  
Yuanfei Han ◽  
Guangfa Huang ◽  
Jianwen Le ◽  
Lihua Du ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Mechanical Behavior ◽  
Volume Fraction ◽  
Extrusion Direction ◽  
Hot Extrusion ◽  
Tensile Tests ◽  
Matrix Composites ◽  
Multi Scale ◽  
Complex Process ◽  
Submicron Scale

Different volume fraction of TiB, TiC and La2O3 multiple-reinforced Ti6Al4V composites were fabricated by casting and followed by forging and hot extrusion. The microstructural evolution and mechanical behavior of (TiB+TiC+La2O3)/Ti6Al4V composites during hot extrusion were investigated. The microstructural observations showed that the TiBw and TiCp agglomeration disappeared and distributed more homogeneously in the Ti matrix after hot extrusion. Besides, TiBw exhibited highly preferred alignment along the extrusion direction and TiCp distributed along the same direction. Besides, two kinds of microstructure bands with distinctive spatial distributions of reinforcements were formed after hot extrusion: equiaxial bands embedded with fairly substantial reinforcements and finer basket-weave bands containing few reinforcements, in which the micron-scale TiBw, TiCp and submicron-scale La2O3 particle stimulating nucleation occurred and resulting dynamic recrystallization were the main mechanisms responsible for grain refinement. The tensile tests revealed that hot extrusion significantly increased elongation of (TiB+TiC+La2O3)/Ti6Al4V composites from 2.71% to 13.2% accompanied by slightly decreasing ultimate tensile strength from 954MPa to 903MPa, compared with that of the as-forged composites, which due to a complex process of reinforcements/matrix interaction during extrusion and dynamic recrystallization.

scholarly journals Texture and Differential Stress Development in W/Ni-Co Composite after Rotary Swaging

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2869
Author(s):  
Pavel Strunz ◽  
Radim Kocich ◽  
David Canelo-Yubero ◽  
Adéla Macháčková ◽  
Přemysl Beran ◽  
...  
Keyword(s):  
Residual Stress ◽  
Room Temperature ◽  
Fiber Texture ◽  
Elliptical Cross ◽  
Rotary Swaging ◽  
Bcc Lattice ◽  
Fcc Lattice ◽  
The Matrix ◽  
Hoop Stresses

Knowledge of texture and residual stresses in tungsten heavy pseudoalloys is substantial for the microstructure optimization. These characteristics were determined in cold and warm rotary swaged W/NiCo composite with help of neutron diffraction. The results were discussed in view of the observed microstructure and mechanical properties. The investigated bars consisted of tungsten agglomerates (bcc lattice) surrounded by NiCo-based matrix (fcc lattice). No preferential crystallographic orientation was found in the as-sintered bar. A strong texture was formed in both the tungsten agglomerates (<101> fiber texture parallel to the swaging axis) and in the NiCo-based matrix (<111> fiber texture) after rotary swaging. Although usually of double-fiber texture, the <001> fiber of the fcc structures was nearly missing in the matrix. Further, the cold-swaged bar exhibited substantially stronger texture for both phases which corresponds to the higher measured ultimate tensile strength. The residual stress differences were employed for characterization of the stress state of the bars. The largest residual stress difference (≈400 MPa) was found at the center of the bar deformed at room temperature. The hoop stresses were non-symmetrical with respect to the swaging axis, which was likely caused by the elliptical cross section of the as-sintered bar.

Microstructure and Mechanical Bevavior of Ni3Al-Matrix Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
P. C. Brennan ◽  
W. H. Kao ◽  
S. M. Jeng ◽  
J.-M. Yang
Keyword(s):  
Yield Strength ◽  
Nickel Aluminide ◽  
Fracture Stress ◽  
Room Temperature ◽  
Hot Extrusion ◽  
Matrix Composites ◽  
The Matrix ◽  
Bend Tests ◽  
Point Bend ◽  
Particulate Reinforced

AbstractAn aluminum oxide particulate-reinforced nickel-aluminide composite was fabricated by vacuum hot pressing and hot extrusion. Room temperature three point bend tests were conducted after 1 and 100 h at 1000 °C. The composite exhibited a decrease in yield strength from 772 to 517 MPa after 100 h while the ultimate fracture stress decreased from 1174 to 998 MPa. The strain to failure increased from 4.6% to 6.0% after the same exposure. Saphikon single crystal Al2O3 fibers were used to demonstrate the materials' compatibility. The fracture surfaces of the failed composites indicated ductile failures in the matrix and decohesion between the particles and matrix.

Fabrication and Characterization of TiNi/AL Smart Composites

2003 ◽  
Vol 785 ◽  
Author(s):  
Gyu Chang Lee ◽  
Jun Hee. Lee ◽  
Young Chul Park
Keyword(s):  
Composite Material ◽  
Shape Memory ◽  
Yield Stress ◽  
Room Temperature ◽  
Volume Fraction ◽  
Matrix Material ◽  
Al Alloy ◽  
Alloy Matrix ◽  
Strain Behavior ◽  
The Matrix

ABSTRACTAn attempt was made to fabricate composite material of an Al alloy matrix reinforced by TiNi shape memory fiber using a hot-press method and to investigate its microstructures and mechanical properties. The analysis of SEM and EDS showed that the composite material had good interface bonding. The stress-strain behavior of the composite material was evaluated at room temperature and 363 K as a function of pre-strain, and it showed that the yield stress at 363 K is higher than that at room temperature. It is also found that the yield stress of the composite material increased with increasing the amount of pre-strain and depended on the volume fraction of the fiber and heat treatment. The smartness of the composite could be given due to the shape memory effect of the TiNi fiber, which generated compressive residual stress in the matrix material when heated after being pre-strained. Microstructural observation revealed that interfacial reactions occurred between the matrix and fiber, creating two intermetallic layers.

Effect of Calcium on Solidification Behavior of Mg-Sn Based Alloys

2009 ◽  
Vol 620-622 ◽  
pp. 169-172 ◽  
Author(s):  
Dae Guen Kim ◽  
Hyeon Taek Son ◽  
Jae Seol Lee
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Solidification Behavior ◽  
Fine Needle ◽  
Microstructure Change ◽  
Ca Addition ◽  
Mg2sn Phase

The effect of Ca addition on microstructure change, precipitation behaviours and mechanical properties, in the present work, of Mg-Sn based alloys were investigated. With increasing of Ca additions, size of the Mg-Sn-Ca ternary phases (A-type) with fine needle shape was decreased and volume fraction of these phase were increased. As Ca was increase from 1 wt.%, 2 wt.%, size and volume fraction of Mg2Sn with coarse needle shape phase (B-type) was increased. However, in 3 wt.% Ca containing alloy, size of these Mg2Sn phase was smaller than that of 2 wt% Ca addition alloy and volume fraction of these phase was decreased.

A Trial of FGM Bearings with Solid Lubricant

2009 ◽  
Vol 631-632 ◽  
pp. 465-470
Author(s):  
Takashi Hashimoto ◽  
Hitoshi Kohri ◽  
Atsushi Yumoto ◽  
Ichiro Shiota
Keyword(s):  
Friction Surface ◽  
Room Temperature ◽  
Electroless Deposition ◽  
Solid Lubricant ◽  
Volume Fraction ◽  
Testing Machine ◽  
High Load ◽  
Lubricant Oil ◽  
The Matrix ◽  
Composite Bearing

It is difficult to use an ordinary plain bearing under a high load or at a high friction speed because lubricant oil is pushed out from the friction surface or deterioration of the lubricant oil is caused by heat of friction. A solid lubricant, MoS2, is promising in such condition. When the lubricant is dispersed in a matrix, the solid lubricant is always supplied from the matrix. Such a composite bearing needs a back metal to maintain its shape. The heat of friction may cause a crack between the bearing and the back metal due to thermal stress. A bearing with low coefficient of friction is necessary to decrease the heat of friction, and an FGM structure is also promising to decrease the stress. The aim of this experiment is to fabricate and to examine friction properties of the composites. Cu was plated on the lubricant particles by electroless deposition. The lubricant volume fraction (hereafter Vf) was up to Vf 30 %. The Cu plated lubricant particles were hot-pressed to form a composite at 873 K under 30 MPa in a vacuum. Friction properties of the composites were determined by using a ball-on-disk type testing machine. The test was performed in the air without oil at room temperature. The solid lubricant in the composites was effective to decrease the coefficients of friction under a high load when the Vf was higher than 20 %.

Normal and Abnormal Fracture Behaviors in Low-Cycle Fatigue of a Unidirectionally Reinforced SCS-6/SP-700 Composite

2004 ◽  
Vol 261-263 ◽  
pp. 1091-1096
Author(s):  
Yasuhiro Yamazaki ◽  
A. Ikada ◽  
M. Okazaki
Keyword(s):  
Titanium Alloy ◽  
Room Temperature ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Low Cycle Fatigue ◽  
Matrix Alloy ◽  
Loading Frequency ◽  
Cycle Fatigue ◽  
The Matrix

Titanium alloy matrix composites (TMCs) have received considerable interest as structural materials for aeronautical applications, because of their higher specific strength and stiffness. When applying TMCs at elevated temperatures, high temperature isothermal low-cycle fatigue (LCF)failure is one of critical issues to be concerned. A unidirectionally reinforced SCS-6/ SP-700 composite is a tentative target in this work, where the matrix alloy, SP-700 is a new generation high strength Titanium alloy developed by NKK Inc., and the SCS-6 is a beta-SiC fiber developed by Textron Specially Materials, respectively. A merit to employ the SP-700 is that this alloy enables to reduce a fabrication temperature, because of its capability for superplasticity at relatively lower temperatures. The 7-plies composite specimen was produced by hot isostatic pressing (HIP) at 800°C for 0.5 hrs. in vacuum, alternating layers of thin-foils of the SP-700 and the green tapes of the SCS-6 fibers, so that the fibers were uniformly distributed as a hexagonal array in the matrix. The volume fraction of the fibers in the composite is about 28 %. In this work, the following articles in a unidirectionally reinforced SCS-6/SP-700 composite have been studied and evaluated: (i)mechanical properties of the SCS-6/SP-700 composite and the matrix alloy at temperatures ranged between room temperature and 450°C; (ii) LCF lives and the failure modes of the composite and the matrix alloy at room temperature and 450°C; (iii) fiber push-out tests at elevated temperatures ranged between room temperature and 600°C, to represent the fiber/matrix interfacial strength; and (iv) observation and the characterization of the interfacial reaction zone by means of a transmission electron microscope (TEM) and an energy dispersive X-ray spectrometer (EDS). Based on these experimental results, the effects of temperature and the loading frequency on LCF failure of the SCS-6/SP-700 composite were discussed.

Fabrication and Mechanical Properties of Ni3Al-Al2O3 Composites

1988 ◽  
Vol 133 ◽  
Author(s):  
C. G. McKamey ◽  
G. L. Povirk ◽  
J. A. Horton ◽  
T. N. Tiegs ◽  
E. K. Ohriner
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Matrix Material ◽  
Hot Extrusion ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Interfacial Structure ◽  
High Temperature Strength ◽  
Four Point Bending ◽  
The Matrix

ABSTRACTThe objective of this study is to develop a metal-matrix composite based on the intermetallic alloy Ni3Al reinforced with Al2O3 fibers, with improved high-temperature strength and lower density compared to the matrix material. This paper summarizes results of initial fabrication and mechanical tests on specimens produced using IC-15 [Ni-24% Al-0.24% B (at.%)] and IC-218 [Ni-16.5% Al-8% Cr-0.4% Zr-0.1% B (at.%)], with 20 vol. % Al2O3 fibers. Fabrication methods include both hot-pressing and hot-extrusion. Mechanical tests include four-point bending and tensile tests. The integrity of the fiber-matrix interface was studied and correlated with mechanical properties. Tensile ductilities of approximately 10% at room temperature were achieved for Ni3Al/Al2O3 composites with controlled material processing and interfacial structure. Fabrication of composites by hot-extrusion produced better tensile properties at room temperature, but superplastic behavior (i.e., low strengths, high ductilities) at 1000°C.

Research on Preparation of Al-Fe-V-Si Alloy Enhanced by In-Situ TiC Particles

2005 ◽  
Vol 475-479 ◽  
pp. 2857-2860
Author(s):  
Bao Hong Zhu ◽  
Yong'an Zhang ◽  
Bai Qing Xiong ◽  
Hong Wei Liu ◽  
Li Kai Shi
Keyword(s):  
Room Temperature ◽  
Volume Fraction ◽  
Hot Extrusion ◽  
Spray Forming ◽  
Forming Process ◽  
Heat Resistant ◽  
Lower Temperature ◽  
In Situ Tic ◽  
Better Than

Heat-resistant Al-Fe-V-Si aluminum alloys enhanced by in-situ TiC particles have been prepared by spray forming process with suitable process parameters. Research results show that the microstructure of as-deposited alloy is fine and homogeneous. In-situ TiC particles prevent the unsteady phases from coming into being. On the other hand, the TiC particles increase the volume fraction of heat-resistant phases. So the mechanical properties of the enhanced alloy by in-situ TiC particles are better than that of Al-Fe-V-Si alloy without TiC particles. The hot extrusion temperature is also an important parameter to understand. Under the permission, it is better to extrude the alloy at lower temperature. The tensile strength of the alloy without TiC particles is about 435MPa at room temperature and is about 204MPa at 350°C. However, when the alloy is enhanced by in-situ TiC particles, the strength of alloy is about 482MPa at room temperature and is about 224MPa at 350°C temperature.

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