Nanoscaled grain boundaries and pores, microstructure and mechanical properties of translucent Yb:[LuxY(1−x)O3] ceramics

2011 ◽  
Vol 509 ◽  
pp. S338-S342 ◽  
Author(s):  
O. Khasanov ◽  
V. Osipov ◽  
E. Dvilis ◽  
A. Kachaev ◽  
A. Khasanov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Microstructure And Mechanical Properties

scholarly journals Microstructure and Mechanical Properties of ZrB2–HfC Ceramics Influenced by HfC Addition

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2046 ◽  
Author(s):  
Yi Jing ◽  
Hongbing Yuan ◽  
Zisheng Lian
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Grain Boundaries ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Weak Interface ◽  
Interface Bonding ◽  
Microstructure And Mechanical Properties ◽  
Small Grains

ZrB2–HfC ceramics have been fabricated using the liquid phase sintering technique at a sintering temperature as low as 1750 °C through the addition of Ni. The effects of HfC addition on the microstructure and mechanical properties of ZrB2–based ceramics have been investigated. These ceramics were composed of ZrB2, HfC, Ni, and a small amount of possible (Zr, Hf)B2 solid solution. Small HfC grains were distributed among ZrB2 grain boundaries. These small grains could improve the density of ZrB2–based ceramics and play a pinning role. With HfC content increasing from 10 wt % to 30 wt %, more HfC grains were distributed among ZrB2 grain boundaries, leading to weaker interface bonding among HfC grains; the relative density and Vickers hardness increased, and flexural strength and fracture toughness decreased. The weak interface bonding for 20 and 30 wt % HfC contents was the main cause of the decrease in both flexural strength and fracture toughness.

Microstructure and mechanical properties of Fe–Al–Nb–B alloys

MRS Advances ◽  
2017 ◽  
Vol 2 (25) ◽  
pp. 1353-1359 ◽  
Author(s):  
Shahbaz Ahmed Azmi ◽  
Alena Michalcová ◽  
Lucia Senčekova ◽  
Martin Palm
Keyword(s):  
Mechanical Properties ◽  
Ternary System ◽  
Grain Boundaries ◽  
Laves Phase ◽  
Uneven Distribution ◽  
Strengthening Effect ◽  
Heusler Phase ◽  
Microstructure And Mechanical Properties ◽  
Al Matrix

ABSTRACTDoping of Fe–Al–Nb alloys with boron results in precipitation of stable C14 Laves phase Nb(Fe,Al)2 instead of metastable Heusler phase Fe2AlNb as in case of the ternary system. The boron stimulated precipitation of the Laves phase leads to preferential precipitation of the Laves phase along grain boundaries and – with higher supersaturation of Nb in the Fe-Al matrix – to an even distribution of additional precipitates within the grains. Though these microstructures seem to be more favourable than in the boron-free alloys, which show an uneven distribution of rather large Laves phase precipitates, no marked strengthening effect by the Laves phase in the Fe–Al–Nb–B alloys is observed.

scholarly journals Effects of Filler Wires on the Microstructure and Mechanical Properties of 2195-T6 Al-Li Alloy Spray Formed by TIG Welding

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3559 ◽  
Author(s):  
Yuhui Zhang ◽  
Huan Li ◽  
Chuanguang Luo ◽  
Lijun Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Grain Boundaries ◽  
Fracture Mode ◽  
Weld Joint ◽  
Space Vehicle ◽  
Fusion Line ◽  
Filler Wire ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties

The main purpose of this work was to investigate the microstructure and mechanical properties of spray-formed 2195-T6 Al-Li alloy welding joints produced by tungsten inert gas (TIG) with Al-Cu and Al-Si-Cu filler wires, so that they can be better used in space vehicle tanks. The porosity analysis indicates that the porosity area of the weld seam with the Al-Si-Cu filler wire is approximately 7.989 times larger than that of the Al-Cu filler wire. Furthermore, the microstructure and microhardness results indicate that the Al/Cu eutectic near the fusion line distributes more at the grain boundaries, while more dispersed Al2Cu phase is found inside the grain, which improves the strength of the joint when using Al-Cu filler wire. However, when using the Al-Si-Cu filler wire, more Si, Cu, and Ti elements are segregated at the grain boundaries, forming a brittle-hard network Al/Cu/Ti eutectic, which reduces the performance of the joint. Additionally, the tensile strength and elongation of the weld joint are about 68.6% and 89.9% of the base metal (BM) when using the Al-Cu filler wire, and can approach the level of friction stir welding (FSW). However, the tensile strength and elongation are only about 56.8% and 39.9%, respectively, of the BM in the weld joint when using the Al-Si-Cu filler wire. Lastly, the fractures both occur on the fusion line and the fracture morphology of the weld joint shows that it is a mixed fracture mode dominated by plastic fracture when using Al-Cu filler wire, while it is mainly a quasi-cleavage fracture mode when using Al-Si-Cu filler wire. Therefore, the joint strength when using Al-Si-Cu filler wire with high strength matching is not as good as that of Al-Cu filler wire with low strength matching.

Effects of Rare Earth Oxides on Microstructures and Properties of Magnesia Refractories

2008 ◽  
Vol 368-372 ◽  
pp. 1158-1160 ◽  
Author(s):  
Bao Guo Zhang ◽  
Zhou Fu Wang ◽  
Shao Wei Zhang ◽  
Xi Tang Wang ◽  
Zi Wei Xu
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Rare Earth ◽  
High Temperature ◽  
Mechanical Strength ◽  
Grain Boundaries ◽  
Bulk Density ◽  
Rare Earth Oxide ◽  
Rare Earth Oxides ◽  
Microstructure And Mechanical Properties

The effects of Y2O3, La2O3 and Nd2O3 on the sintering, microstructure and mechanical properties of magnesia refractories were investigated. Addition of rare earth oxide (ReO) to magnesia refractories increases the bulk density, decreases the porosity and improves the mechanical strength of the refractories. The improved sinterability was attributable to the vacancies generation associated with the solid-solution reactions between MgO and ReO. In the samples with ReO, rare earth silicate phases form at magnesia grain boundaries, providing additional bonding between magnesia grains and between magnesia grains and matrix. Consequently, the samples with ReO showed much higher high temperature strengths than those without ReO.

scholarly journals Improving mechanical properties of ZK60 magnesium alloy by cryogenic treatment before hot extrusion

2020 ◽  
Vol 39 (1) ◽  
pp. 200-208
Author(s):  
Tao Lin ◽  
Ji-Xue Zhou ◽  
Cai-Nian Jing ◽  
Yun-Teng Liu ◽  
Lin-Lin Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Grain Boundaries ◽  
Cryogenic Treatment ◽  
Hot Extrusion ◽  
Microstructure And Mechanical Properties ◽  
Zk60 Alloy ◽  
Nonferrous Alloys ◽  
Zk60 Magnesium Alloy

AbstractFew studies of cryogenic treatment were focused on nonferrous alloys, such as magnesium alloy. In this work, the effect of cryogenic treatment (77 K) before extrusion on microstructure and mechanical properties of ZK60 alloy was investigated. The results showed that many fine G.P. zones were formed during the cryogenic treatment and then grew to short fine {\beta }_{1}^{^{\prime} } precipitates when heating before extrusion. These precipitates pinned dynamic recrystallized grain boundaries in the subsequent extrusion, resulting in fine gains and dispersed spherical precipitates. By the cryogenic treatment before extrusion, the extruded ZK60 alloy showed good tensile strength and elongation balance. Especially, elongation was improved by 29%.

scholarly journals Microstructure and Mechanical Properties of Spark Plasma Sintered and Severely Deformed AA7075 Alloy

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1433
Author(s):  
Dariusz Garbiec ◽  
Volf Leshchynsky ◽  
Andrea García-Junceda ◽  
Radosław Swadźba ◽  
Piotr Siwak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Shear Bands ◽  
High Strength ◽  
Ultrafine Grain ◽  
Fine Grained ◽  
Severe Deformation ◽  
Microstructure And Mechanical Properties ◽  
Spark Plasma

In this paper, the microstructure and mechanical properties of AA7075 with a coarse-fine-grained laminated microstructure produced by spark plasma sintering (SPS) and the cyclic extrusion severe deformation (KOBO) technique were investigated. It was found that an inhomogeneous grain microstructure was formed from coarse and fine grains by the SPS process and then was transformed into a coarse-fine-grained laminated microstructure by means of KOBO extrusion at room temperature. The grain refinement during KOBO extrusion resulted in a fine grained laminated microstructure created due to the formation of low-angle grain boundaries (LAGBs), followed by dynamic recrystallization, leading to high-angle grain boundaries (HAGBs). The EBSD analysis results reveal the formation of a deformed and partially recrystallized ultrafine grain microstructure owing to the generation and development of shear bands during KOBO extrusion. The ultimate tensile strength (UTS) of the AA7075 alloy rose after SPS-KOBO severe deformation up to 422 MPa, with high strains of about 33%. The obtained results clearly show that the SPS-KOBO extrusion technique allows a bimodal laminated fine gradient grain microstructure to be obtained due to deformation and dynamic recrystallization, which result in both high strength and good ductility. The new heterogeneous AA7075 alloys obtained by the SPS-KOBO combined techniques demonstrate that microstructural heterogeneities can assist in overcoming the strength–ductility trade-off.

Microstructure and mechanical properties of the Sanicro 25 steel after ageing

2018 ◽  
Vol 1 (91) ◽  
pp. 5-11
Author(s):  
A. Merda ◽  
M. Sroka ◽  
K. Klimaszewska ◽  
G. Golański
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Hardness Measurement ◽  
Austenitic Steels ◽  
Precipitate Morphology ◽  
Microstructural Investigation ◽  
Σ Phase ◽  
Steel Microstructure ◽  
Microstructure And Mechanical Properties ◽  
Secondary Precipitates

Purpose: The purpose of the research was to determine and analyse the changes in the microstructure and mechanical properties of the Sanicro 25 steel in the as-received condition and after ageing at 600, 650 and 700°C for up to 10,000 hours. Design/methodology/approach: The scope of the investigations included: microstructural investigation – SEM microscopy, analysis of precipitation performed using TEM microscopy, investigation of mechanical properties, Vickers hardness measurement. Findings: In the as-received condition, the Sanicro 25 steel was characterised by austenitic microstructure with annealing twins and numerous primary precipitates. The analysis of Sanicro 25 steel microstructure after ageing at 600 and 700°C for up to 10,000 hours revealed significant changes in the microstructure consisting mainly in a tendency to create unfavourable morphology of secondary precipitates – M23C6 carbides that form continuous carbide systems along the grain boundaries. The observations have shown that during long-term ageing the secondary carbides were also precipitated inside the grains and at the interface of three grain boundaries – σ phase. Research limitations/implications: The analysis of the microstructure of the examined steel using SEM and TEM was performed to determine the influence of ageing on the processes of changes in the precipitate morphology. Practical implications: The results obtained based on the performed research constitute a building block for the degradation characteristics of the microstructure and mechanical properties of the 23/25-type austenitic steels. Originality/value: The results of the investigation and analysis of the metallographic and mechanical properties of the Sanicro25 austenitic steel in as-received condition and after ageing are presented.

Effects of Long-Term Aging at 1070°C on Microstructure and Mechanical Properties of Ni3Al-Base Alloy IC6E

2010 ◽  
Vol 650 ◽  
pp. 205-209 ◽  
Author(s):  
Ming Li ◽  
Jin Xia Song ◽  
Shu Suo Li ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Base Alloy ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Microstructure And Mechanical Properties ◽  
Stress Rupture Properties ◽  
Essential Change

The effect of long-term aging at 1070°C on microstructure and mechanical properties of Ni3Al-base equiaxed superalloy IC6E was investigated. The microstructure change during aging for periods of 100 to 1500h was examined by SEM . Results showed that alloy IC6E underwent following microstructure changes during aging: γ' phases coalesced and grew, γ phases became disconnected and coarsened, the content of Mo (the solution-hardening element of γ and γ' phases) in γ' phases decreased, Y-NiMo phases precipitated from γ phases both at grain boundaries and within grains, and γ' bands and large γ phases emerged along grain boundaries. The tensile and stress rupture properties after aging were determined. The results showed that the yield strength of alloy IC6E at room temperature decreased obviously after aging for 100 h, and reduced slowly during further aging. The stress rupture life under 1070°C, 80MPa also had no essential change during aging.

Influence of Rare Earth Additions on the Microstructure and Mechanical Properties of Al7Si0.3Mg Alloys Processed by Semi-Solid Die Casting and Gravity Die Casting

2019 ◽  
Vol 285 ◽  
pp. 69-74 ◽  
Author(s):  
Long Fei Li ◽  
Da Quan Li ◽  
Min Luo ◽  
Yong Zhong Zhang ◽  
Yong Lin Kang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Grain Boundaries ◽  
Die Casting ◽  
Eutectic Phase ◽  
Microstructure And Mechanical Properties ◽  
Die Cast ◽  
Rare Earth Additions ◽  
Semi Solid

Microstructures with fine globular grains and refined eutectic structures are important to enhance the mechanical properties of A356 alloys processed by semi-solid and gravity die casting. Rare earth (RE) additions have been shown to be capable of refining both the α-Al particles as well as modify the eutectic phase of alloys. In semi-solid die casting, Al7Si0.3Mg alloys with RE concentrations (0, 0.1 and 0.4 wt.%) were used to prepare semi-solid slurries using the SEED (Swirling Enthalpy Equilibrium Device) method, and subsequently semi-solid die cast. The same compositions of alloys were also applied to gravity die casting. The microstructure and mechanical properties of castings in two processes have been characterized. Compared to the grains produced in gravity die casting, globular grains with small size (260 μm) in the semi-solid die casting significantly enhance the UTS and elongation of alloys. Although the size of grains had no change with increasing RE concentrations in alloys. The Al-Si eutectics were changed to refined morphology with the 0.1 wt.% RE addition, which enhanced the ductility of alloys in two processes. When increasing the RE addition to 0.4 wt.%, the RE-rich phases precipitated at grain boundaries, which decreased the UTS and elongation of alloys.

Microstructure and Mechanical Properties of Friction Stir Welded Al-Zn-Mg-Cu Alloy

2014 ◽  
Vol 628 ◽  
pp. 7-11
Author(s):  
Sheng Dan Liu ◽  
Yun Dai ◽  
Yu Long Wu ◽  
Bin Chen ◽  
Xin Ming Zhang
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Base Material ◽  
Optical Microscope ◽  
Alloy Sheet ◽  
Grain Structure ◽  
Hardness Profile ◽  
Friction Stir ◽  
Cu Alloy ◽  
Microstructure And Mechanical Properties

The microstructure and mechanical properties of friction stir welded Al-Zn-Mg-Cu alloy sheet were investigated by means of hardness and tensile tests, optical microscope and scanning electron microscope. The hardness profile of the weld exhibits a W shape with the lowest value in the thermo-mechanically affected zone on the advancing side. The tensile strength and elongation of the weld are about 71% and 72% that of the base material. In the nugget zone, there are a number of fine recrystallized grains and dispersed precipitates at grain boundaries. In the thermo-mechanically affected zone, the grain size is not uniform and there are a number of precipitates at grain boundaries. In the heat affected zone, the grain structure is similar to the base material.

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