scholarly journals Study on Porous Mg-Zn-Zr ZK61 Alloys Produced by Laser Additive Manufacturing

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 635 ◽  
Author(s):  
Min Zhang ◽  
Changjun Chen ◽  
Chang Liu ◽  
Shunquan Wang
Keyword(s):  
Additive Manufacturing ◽  
Surface Morphology ◽  
Laser Energy ◽  
Laser Additive Manufacturing ◽  
Solid Solution Strengthening ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Solution Strengthening ◽  
Precipitated Phases

This study reports the effect of Zn contents on surface morphology, porosity, microstructure and mechanical properties of laser additive manufacturing (LAM) porous ZK61 alloys. The surface morphology and porosity of the LAMed porous ZK61 alloys depend on the laser energy input. With increasing Zn contents, the surface quality of porous Mg-Zn-Zr alloys became worse, the grains are obviously refined and the precipitated phases experienced successive transitions: MgZn → MgZn + Mg7Zn3 → Mg7Zn3. The microhardness was improved significantly and ranged from 57.67 HV to 109.36 HV, which was ascribed to the fine grain strengthening, solid solution strengthening and precipitation strengthening. The LAMed porous Mg-15 wt.% Zn-0.3 wt.% Zr alloy exhibits the highest ultimate compressive strength (73.07 MPa) and elastic modulus (1.785 GPa).

Comprehensive Strengthening of Microalloyed Pure Gold

2015 ◽  
Vol 713-715 ◽  
pp. 2617-2623
Author(s):  
Jun Ping Yuan ◽  
Chun Yu Ma ◽  
Chang Wang
Keyword(s):  
Solid Solution ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Pure Gold ◽  
Solid Solution Strengthening ◽  
Fine Grain ◽  
Performance Requirements ◽  
Fine Grain Strengthening ◽  
Solution Strengthening ◽  
And Performance

The hardness of pure gold jewellery is low which makes it difficult to meet structural design and performance requirements, and restricts its artistic value. In this research, scandium, calcium, and magnesium were used as alloying elements with pure gold, and the microstructure and hardening behaviour of modified pure gold were studied through cold-working, solid solution, and aging treatment. The results showed that the as-cast hardness of an Sc-Ca-Mg alloyed pure gold could reach HV64: after solution treatment at 700 °C, the hardness could reach HV55, and the microstructure in its solid solution state presented a homogeneous single phase. When the modified pure gold was deformed and the deformation rate reached 80%, the hardness reached HV118, after aging treatment at 250 °C and small precipitation phases were dispersed in its structure; the resultant grain size was finer than that of pure gold, and the hardness reached HV133. The hardening behaviour of this modified pure gold was the comprehensive effect of solid solution strengthening, fine-grain strengthening, deformation strengthening, and precipitation strengthening.

Microstructure and Mechanical Properties of Backward-Extruded Mg-Zn-xCa Biomaterials

2013 ◽  
Vol 747-748 ◽  
pp. 426-430
Author(s):  
Xue Jun Li ◽  
Hui Li ◽  
Shuang Shuang Zhao ◽  
Ning Ma ◽  
Qiu Ming Peng
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Solid Solution Strengthening ◽  
Backward Extrusion ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Microstructure And Mechanical Properties ◽  
Solution Strengthening ◽  
Extrusion Technology ◽  
Precipitate Strengthening

The Mg-1.0Zn-xCa (x=0.2, 0.5, 0.8, 1 wt. %) alloys were prepared by zone solidification and backward extrusion technology. The microstructure and mechanical properties of backward-extruded Mg-1.0Zn-xCa alloys were investigated. The results showed that these backward-extruded Mg-1.0Zn-xCa alloys were mainly composed of equi-axed pentagon-shaped grains and some Mg0.9Zn0.03 precipitates. The tensile and compressive strengths of backward-extruded Mg-1.0Zn-xCa alloys were greatly improved. The improved mechanical properties are mostly attributed to fine grain strengthening, solid solution strengthening and precipitate strengthening. The results demonstrated that the micro alloying of Ca element was one of effective method to improve the mechanical properties of Mg-1.0Zn based biomaterials.

Study on the Precipitation Behavior of Precipitates of 7075 Aluminum Alloy Friction Stir Welding Joint

2020 ◽  
Vol 1003 ◽  
pp. 37-46
Author(s):  
Hao Zhu ◽  
Shao Kang Dong ◽  
Ze Ming Ma ◽  
Jun Wang
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Strain Hardening ◽  
Strengthening Effect ◽  
7075 Aluminum Alloy ◽  
Friction Stir ◽  
Microhardness Distribution ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Precipitated Phases

In this work, the microhardness of 7075 aluminum alloy friction stir welding (FSW) joint was measured by a micro vickers hardness tester, the microstructure of the joints was characterised by microscope, the precipitated phases among the welding nugget zone (WNZ), thermal mechanical affected zone (TMAZ), heat affected zone (HAZ) were affirmed by X-ray diffractometer (XRD) and the lattice fringe of transmission electron microscopy (TEM) high resolution image. Based on this, the precipition behavior of precipitated phases was studied. The results show that the microhardness distribution of the 7075 aluminium alloy FSW joints is heterogeneous in comparison with the base metal (BM). The precipitates in the joint mainly include MgZn rod shape and AlCuMg in elliptical shape. In the WNZ, the main precipitate is AlCuMg, and the fine grain strengthening effect is better, so the microhardness in this zone is relatively high. In the TMAZ, the quantity of AlCuMg decreased while the MgZn2 increased relatively in comparison with the WNZ. At the same time, the effect of the fine grain strengthening was weakened, though the strain hardening increased. Therefore, the microhardness in the TMAZ still decreased. In the HAZ, the quantity of MgZn2 increased furtherly, and there is no strain hardening and fine grain strengthening, so the microhardness of the HAZ was the lowest among the FSW joints. Besides, through comparative tests, the optimal process parameters of friction stir welding of 7075 aluminum alloy were obtained.

scholarly journals Effect of Nb on the Microstructure and Mechanical Properties of Ti2Cu Intermetallic through the First-Principle Calculations and Experimental Investigation

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 547 ◽  
Author(s):  
Jialin Cheng ◽  
Yeling Yun ◽  
Jingjing Wang ◽  
Jiaxin Rui ◽  
Shun Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Density Functional ◽  
Covalent Bond ◽  
First Principle ◽  
Compression Tests ◽  
Solid Solution Strengthening ◽  
First Principle Calculations ◽  
Fine Grain ◽  
Fine Grain Strengthening

Through the first-principle calculations based on density functional theory and experimental investigation, the structural stability elastic properties and mechanical properties of Ti2Cu and Ti18Cu5Nb1 intermetallics were studied. The first-principle calculations showed that the ratio of bulk modulus to shear modulus (B/G) and Poisson’s ratio (ν) of Ti2Cu and Ti18Cu5Nb1 intermetallics were 2.03, 0.288, and 2.22, 0.304, respectively, indicating that the two intermetallics were ductile. This was confirmed by the compression tests, which showed that the plastic strain of both intermetallics was beyond 25%. In addition, the yield strength increased from the 416 to 710 MPa with the addition of Nb. The increase in strength is the result of three factors, namely covalent bond tendency, fine grain strengthening, and solid solution strengthening. This finding gives clues to design novel intermetallics with excellent mechanical properties by first-principle calculations and alloying.

Characterization of LAM-Fabricated Porous Superalloys for Turbine Components

2016 ◽  
Author(s):  
Brandon Ealy ◽  
Luisana Calderon ◽  
Wenping Wang ◽  
Jay Kapat ◽  
Ilya Mingareev ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Porous Structure ◽  
Turbine Blade ◽  
Leading Edge ◽  
Laser Additive Manufacturing ◽  
Internal Impingement ◽  
Edge Segment ◽  
Cycle Efficiency ◽  
Non Destructive

The limits of gas turbine technology are heavily influenced by materials and manufacturing capabilities. Inconel alloys remain the material of choice for most hot gas path components in gas turbines, however recent increases in turbine inlet temperature (TIT) are associated with the development of advanced convective cooling methods and ceramic thermal barrier coatings (TBC). Increasing cycle efficiency and cycle specific work are the primary drivers for increasing TIT. Lately, incremental performance gains responsible for increasing the allowable TIT have been made mainly through innovations in cooling technology, specifically convective cooling schemes. An emerging manufacturing technology may further facilitate the increase of allowable maximum TIT, thereby impacting cycle efficiency capabilities. Laser Additive Manufacturing (LAM) is a promising manufacturing technology that uses lasers to selectively melt powders of metal in a layer-by-layer process to directly manufacture components, paving the way to manufacture designs that are not possible with conventional casting methods. This study investigates manufacturing qualities seen in LAM methods and its ability to successfully produce complex features found in turbine blades. A leading edge segment of a turbine blade, containing both internal and external cooling features, along with an engineered-porous structure is fabricated by laser additive manufacturing of superalloy powders. Various cooling features were incorporated in the design, consisting of internal impingement cooling, internal lattice structures, and external showerhead or transpiration cooling. The internal structure was designed as a lattice of intersecting cylinders in order to mimic that of a porous material. Variance distribution between the design and manufactured leading edge segment are carried out for both internal impingement and external transpiration hole diameters. Through a non-destructive approach, the presented geometry is further analyzed against the departure of the design by utilizing x-ray computed tomography (CT). Employing this non-destructive evaluation (NDE) method, a more thorough analysis of the quality of manufacture is established by revealing the internal structures of the porous region and internal impingement array. Flow testing was performed in order to characterize the uniformity of porous regions and flow characteristics across the entire article for various pressure ratios (PR). Discharge coefficient of internal impingement arrays and porous structure are quantified. The analysis yields quantitative data on the build quality of the LAM process, providing insight as to whether or not it is a viable option for manufacture of micro-features in current turbine blade production.

scholarly journals Improving Mechanical Properties of Mg–Sc Alloy by Surface AZ31 Layer

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2021
Author(s):  
Cheng Zhang ◽  
Cheng Peng ◽  
Jin Huang ◽  
Yanchun Zhao ◽  
Tingzhuang Han ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hot Extrusion ◽  
Grain Structure ◽  
Gradient Structure ◽  
Alloy Structure ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Gradient Microstructure ◽  
Solution Strengthening ◽  
Dislocation Strengthening

Building a gradient structure inside the Mg alloy structure can be expected to greatly improve its comprehensive mechanical properties. In this study, AZ31/Mg–Sc laminated composites with gradient grain structure were prepared by hot extrusion. The microstructure and mechanical properties of the Mg–1Sc alloy with different extrusion temperatures and surface AZ31 fine-grain layers were investigated. The alloy has a more obvious gradient microstructure when extruded at 350 °C. The nanoscale hardness value of Mg–1Sc alloy was improved through fine-grain strengthening and solution strengthening of the surface AZ31 fine-grain layer. The strength of Mg–1Sc alloy was improved due to the fine-grain strengthening and dislocation strengthening of the surface AZ31 fine-grain layer, and the elongation of Mg–1Sc alloy was increased by improving the distribution of the microstructure.

Influence of fine-grain and solid-solution strengthening on mechanical properties and in vitro degradation of WE43 alloy

2014 ◽  
Vol 9 (1) ◽  
pp. 015014 ◽  
Author(s):  
Dexue Liu ◽  
Yutian Ding ◽  
Tingbiao Guo ◽  
Xiaoqiong Qin ◽  
Chenggong Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
In Vitro Degradation ◽  
Solid Solution Strengthening ◽  
Fine Grain ◽  
Solution Strengthening ◽  
We43 Alloy

Influence of nanostructured Cu on the mechanical properties of Cu–MWCNTs composites

2020 ◽  
Vol 111 (6) ◽  
pp. 469-478
Author(s):  
Lailesh Kumar ◽  
Santosh Kumar Sahoo ◽  
Syed Nasimul Alam
Keyword(s):  
Wear Mechanisms ◽  
Mechanical Milling ◽  
Wear Behavior ◽  
Homogeneous Distribution ◽  
Wear Properties ◽  
Multiwalled Carbon ◽  
Solid Solution Strengthening ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Dispersion

Abstract In the present investigation, Cu-multiwalled carbon nanotubes (MWCNTs) nanocomposites were developed through mechanical milling using nanostructured Cu as a matrix and MWCNTs as nanofillers. The influence of nanostructured Cu on the microstructure, microhardness, and wear behavior of Cu-MWCNTs nanocomposites was also studied. The crystallite size of nanostructured Cu powder via mechanical milling for 25 h was found to be 16 nm. The major challenge associated with the development of Cu-MWCNTs nanocomposites is the uniform dispersion of the CNTs in the Cu matrix, which was addressed by incorporating nanostructured Cu, leading to the homogeneous distribution of CNTs and good bonding between the CNTs and the Cu matrix. A significant improvement in relative density and microhardness with <3 wt.% MWCNTs was observed compared to pure asreceived Cu and its composites. The hardness of Cu-3 wt.% MWCNTs nanocomposite developed using nanostructured Cu were achieved at <800 MPa, which is about 2.3 times higher than that of the as-received Cu sample (~ 359 MPa). The significant increment in mechanical and wear properties mainly originates from fine-grain strengthening effects and solid solution strengthening. The wear mechanisms in the various nanostructured Cu-MWCNTs composites were studied in detail and oxidation wear was identified as one of the main wear mechanisms.

Effect of Laser Energy Density on Bulk Properties of SS 316L Structures Built by Laser Additive Manufacturing Using Powder Bed Fusion

2019 ◽  
Author(s):  
Saurav K. Nayak ◽  
Sanjay K. Mishra ◽  
Christ P. Paul ◽  
Arackal N. Jinoop ◽  
Sunil Yadav ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Energy Density ◽  
Layer Thickness ◽  
Laser Energy ◽  
Advanced Technology ◽  
Incomplete Fusion ◽  
Laser Energy Density ◽  
Powder Bed Fusion ◽  
Laser Additive Manufacturing ◽  
Powder Bed

Abstract Laser Additive Manufacturing using Powder Bed Fusion (LAM-PBF) is one of the revolutionary technologies playing a key role in fourth industrial revolution for redefining manufacturing from mass production to mass customization. To upkeep the pace, Raja Ramanna Centre for Advanced Technology (RRCAT) has indigenously developed an LAM-PBF system and it is being used for process and component development for various engineering applications. This paper reports a parametric investigation to evaluate the influence of process parameters on the sample properties and to develop the process window for fabricating complex shaped engineering components. In the present work, an experimental investigation is carried out to investigate the effect of Laser Energy density (LED) on the porosity, microstructure and mechanical properties of SS 316L bulk structures fabricated by LAM-PBF system. LED is a combined parameter simultaneously considering the effect of Laser Power (P), Scan Speed (v), hatch spacing (h) and layer thickness (t). The effect of three LED values such as 83.33 J/mm3, 253.97 J/mm3 and 476.19 J/mm3 is investigated in the present work by building cuboidal samples at a layer thickness of 75 microns. Porosity is estimated using area fraction method in optical microscopy and it is found that the minimum porosity of 0.14 % and pore area of 1.28 mm2 are observed at 253.97 J/mm3. Maximum porosity of 18.85 % is observed at 83 J/mm3 due to incomplete fusion defects. However, porosity observed at 475 J/mm3 is 6.56 % with average pore size of 17.8 mm2. Microstructural studies show primarily columnar growth in all the samples with fine dendrites. The dendrite size is observed to be 3.2 μm, 2.4 μm and 1.46 μm at 83.33 J/mm3, 253.97 J/mm3 and 476.19 J/mm3 respectively. Micro-hardness and single cycle automatic ball indentation studies are found to be in agreement with dendritic size, with lower hardness at larger dendrite size. X-Ray Diffraction (XRD) studies indicate similar peaks at all the conditions, with slight peak shift observed with increase in LED primarily due to higher amount of residual stress. Thus, it can be inferred that LED of 253.97 J/mm3 is suitable for fabricating engineering components due to combination of lower porosity and fine dendritic structure.

Effect of Co on microstructure and mechanical properties of precipitation hardening stainless steel

2020 ◽  
Vol 117 (1) ◽  
pp. 116
Author(s):  
Xiang LV ◽  
De-ning Zou ◽  
Jiao Li ◽  
Yang Pang ◽  
Yu-nong Li
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Stainless Steel ◽  
Precipitation Hardening ◽  
Volume Fraction ◽  
X Ray ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Transmission Electron ◽  
Solution Strengthening

The effects of Co element on the microstructure of precipitation hardening stainless steel was investigated by metallographic microscope (OM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD), and the mechanical properties were measured by tensile, hardness and impact tests. The results show that with increasing Co content, the volume fraction of reversion austenite is increased. The precipitation of ε-Cu phase is remarkably decreased, leading to the improvement of ductility, while the strength and hardness are decreased. Co element improves the strength and toughness of stainless steel through fine-grain strengthening, solution strengthening and austenitic toughening.

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