Influence of Ageing Heat Treatment on Microstructure and Mechanical Properties of a Secondary Rheocast AlSi9Cu3(Fe) Alloy

2015 ◽  
Vol 828-829 ◽  
pp. 212-218 ◽  
Author(s):  
Stefano Capuzzi ◽  
Giulio Timelli ◽  
Alberto Fabrizi ◽  
Franco Bonollo
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Optical Microscope ◽  
Micro Hardness ◽  
Hardness Testing ◽  
Microscopy Technique ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Al Matrix

The effects of different process parameters (temperature and time) during the ageing treatment on the microstructure and the mechanical properties of a secondary rheocast AlSi9Cu3(Fe) alloy have been examined. Optical microscope investigations have been performed to qualitatively study the microstructure of the as-rheocast and thermal treated alloys. Transmission electron microscopy technique and selected area electron diffraction analyses have been used to characterize the hardening phases precipitated in the Al-matrix during the different ageing stages. The evolution of mechanical properties of the Al matrix has been monitored by micro-hardness testing.

The orientation relationships of nanobelt-like Si2Hf precipitates in an Al–Si–Mg–Hf alloy

2016 ◽  
Vol 49 (4) ◽  
pp. 1223-1230 ◽  
Author(s):  
Xueli Wang ◽  
Huilan Huang ◽  
Xinfu Gu ◽  
Yanjun Li ◽  
Zhihong Jia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Coincident Site Lattice ◽  
Orthorhombic Structure ◽  
Orientation Relationships ◽  
Lattice Distribution ◽  
Site Lattice ◽  
Transmission Electron ◽  
Habit Planes ◽  
Al Matrix

The orientation relationships (ORs) between the Al matrix and Si2Hf precipitates with an orthorhombic structure in an Al–Si–Mg–Hf alloy after heat treatment at 833 K for 20 h were investigated by transmission electron microscopy and electron diffraction. Four ORs are identified as (100)Al||(010)p, (0\overline {1}1)Al||(101)pand [011]Al||[\overline {1}01]p; (11\overline {1})Al||(010)pand [011]Al||[\overline {1}01]p; (12\overline {1})Al||(010)p, (101)Al||(100)pand [1\overline {11}]Al||[001]p; (\overline {11}1)Al||(010)pand [112]Al||[\overline {1}01]p. The habit planes of these four ORs are rationalized by the fraction of good atomic matching sites at the interface. In addition, the formation of Si2Hf precipitates with a nanobelt-like morphology is interpreted on the basis of the near-coincident site lattice distribution.

Investigation on Recovery and Recrystallization of Al-Si-Al2O3 Composites

2013 ◽  
Vol 813 ◽  
pp. 345-350
Author(s):  
Xiong Wei Wang ◽  
Xiao Song Jiang ◽  
De Gui Zhu ◽  
Luo Zhang
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Optical Microscope ◽  
In Situ Synthesis ◽  
Recrystallization Temperature ◽  
Recrystallization Behavior ◽  
Micro Hardness ◽  
Hardness Tester ◽  
Scanning Electron

Al-Si-Al2O3 composites were prepared by powder metallurgy with in-situ synthesis technology. The recovery and recrystallization behavior of Al-Si-Al2O3 composites which underwent compression and then heat-treatment under different temperature were studied using micro-hardness tester, optical microscope (OM) and scanning electron microscopy (SEM) . The results showed that the hardness of composites increased dramatically after compression, and the sample containing 5wt% Si was increasing more evidently than the sample including 10wt%Si. Heat treatment gradually eliminated work hardening; meanwhile the fact that the hardness of composites trended to decline greatly when subjected to annealing suggested occurrence of recovery and recrystallization inside the composites. Recrystallization nucleation preferentially took place in the region near the particle, while the growth of recrystallized grains can also be hindered owning to the pining effect of particles. Depending on the analysis of microstructure and microhardness, it can be concluded that the recrystallization temperature of Al-wt.5%Si-Al2O3 composites was 500°C and the Al-wt.10%Si-Al2O3 composites was 525°C.

scholarly journals Effects of Solidification Pressure and Heat Treatment on the Microstructure and Micro-Hardness of AlSi9CuMg Alloy

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2229
Author(s):  
Lijun Wei ◽  
Baoshuai Han ◽  
Fan Ye ◽  
Yanjin Xu ◽  
Sujun Wu
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
High Pressure ◽  
Early Stage ◽  
Micro Hardness ◽  
Transmission Electron ◽  
Ageing Processes ◽  
Hardness Change ◽  
Solidification Pressure ◽  
Peak Value

The effect of high pressure (135 MPa) and the following heat treatment on the microstructure and micro-hardness of the squeezing cast AlSi9CuMg alloy is investigated, using optical microscopy (OM), Vickers tester, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicate that the application of high pressure can increase under-cooling and the cooling rate during solidification and cause the refinement of the microstructure. The enhanced melt flow resulting from high pressure can also break the dendrite to form the spherical and elliptical primary α (Al) grains during the early stage of solidification. The winter-sweet flower-shaped primary α (Al) phases can also be formed through plastic deformation caused by the flow of the partially solidified melt. The ageing treatment results showed that a maximum (peak) micro-hardness value was obtained for each of the three ageing temperatures at different ageing times, and the highest peak value was achieved at 175 °C for 480 min. The micro-hardness change of the sample under different ageing processes was attributed to the variation of type, density, and size of the precipitates.

Characterization of Microstructure and Mechanical Properties of a Nb-Microalloyed Steel after Quenching-Partitioning-Tempering Process

2010 ◽  
Vol 654-656 ◽  
pp. 90-93 ◽  
Author(s):  
Xiao Dong Wang ◽  
Zheng Hong Guo ◽  
Yong Hua Rong
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Treatment Process ◽  
Microalloyed Steel ◽  
Heat Treatment Process ◽  
Step Process ◽  
Transmission Electron ◽  
Nb Microalloyed Steel ◽  
Tempering Process

A novel heat treatment process, that is, quenching-partitioning-tempering (Q-P-T) process, has been developed as a new way to obtain ultrahigh strength martensitic structural steel containing retained austenite and alloying carbide. In order to display merit of the Q-P-T process, a medium carbon Nb-microalloyed steel is treated by Q-P-T 1-step process and Q-P-T 2-step process, as well as treated by the transformation induced plasticity heat treatment process and quenching and tempering process, respectively. The results show that Q-P-T samples possess better mechanical properties than those treated by other heat treatment processes. The origin of the good mechanical properties is analyzed based on the phase and microstructure characterization using X-ray diffraction, scanning electron microscopy and transmission electron microscopy.

Effect of Heat Treatment Process on Microstructure and Properties in Low Carbon Si-Mn Q&P Steel

2011 ◽  
Vol 233-235 ◽  
pp. 1009-1013
Author(s):  
Cai Zhao ◽  
Di Tang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Retained Austenite ◽  
Treatment Process ◽  
Lath Martensite ◽  
Heat Treatment Process ◽  
Low Carbon ◽  
Transmission Electron ◽  
Partitioning Time

The mechanical properties of Low Carbon Si-Mn Q&P steel are strongly affected by the conditions of heat treatment. Microstructures and mechanical properties of Low Carbon Si-Mn Q&P steel at different partitioning temperature and holding time was investigated. The microstructure was analysed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is shown that the microstructure of Q&P steel is carbon-depleted lath martensite and carbon enriched retained austenite. The retained austenite appear film-type between the laths. Higher partitioning temperature and longer partitioning time can obtain more retained austenite. It is shown that with increasing partitioning time ultimate tensile strength decreases, while elongation increases obviously. Carbon-enriched metastable retained austenite is considered beneficial because the TRIP phenomenon during deformation can contribute to formability and energy absorption.

Influence of Quenching-Tempering on the Carbide Precipitation of 2.25Cr-1Mo-0.25V Steel Used in Reactor Pressure Vessels

2019 ◽  
Author(s):  
Yafei Wang ◽  
Songyan Hu ◽  
Guangxu Cheng ◽  
Zaoxiao Zhang ◽  
Jianxiao Zhang
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Pressure Vessels ◽  
Carbide Precipitation ◽  
Amorphous Films ◽  
Replica Technique ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Before And After ◽  
Reactor Pressure

Abstract The carbide precipitation of 2.25Cr-1Mo-0.25V steel is studied during the head-fabrication heat treatment process using gold replica technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Shapes, structures and sizes of carbides before and after heat treatment are analyzed. The dissolution of strip-shaped carbides and the precipitation of granular carbides are confirmed. Amorphous films at the boundaries of carbides are observed by high-resolution transmission electron microscope (HRTEM), which is formed due to the electron irradiation under TEM.

Effect of Heat-Treatment on the Mechanical Properties of TiB2P/2024Al Composite

2007 ◽  
Vol 353-358 ◽  
pp. 1322-1325
Author(s):  
Long Tao Jiang ◽  
Min Zhao ◽  
Rui Jun Fan ◽  
Shao Lei Xu ◽  
De Zhi Zhu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Squeeze Casting ◽  
Hardness Measurement ◽  
Obvious Effect ◽  
Casting Technology ◽  
Transmission Electron ◽  
Peak Aged

55vol% TiB2P/2024Al composite was fabricated by squeeze casting technology, and the effect of heat treatment on mechanical properties of the composites was studied by means of hardness measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile testing etc. Results show that heat treatment has remarkable influence on the hardness and the tensile strength of the composites. For TiB2P/2024Al composites, the composites aged at 130°C for 5h can obtain the highest hardness, and the composites peak-aged at 160°C and aged at 190°C for 24h can obtain the higher tensile strength, which is due to the type of precipitates in the composites. Considering the experimental error, heat treatments has no obvious effect on elastic modulus of the experimental composite.

Microstructure and Mechanical Properties of Mg-9Al-6.5Ca-3Zn-0.6Mn-XNd Alloys Prepared by Spray Forming

2011 ◽  
Vol 117-119 ◽  
pp. 1447-1452
Author(s):  
Guo Wei Zhang ◽  
Zheng Chen ◽  
Wei Chen ◽  
Hai Ying Xin ◽  
Jing Zhai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Scanning Electron Microscopy ◽  
Spray Forming ◽  
Protective Atmosphere ◽  
Forming Technology ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron ◽  
Scanning Electron

The Mg-9Al-3Zn-0.6Mn-xNd alloys, preformed with φ300mm size, has been prepared by spray forming technology under a protective atmosphere. The microstructure and mechanical properties have been investigated by XRD, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and strengths tested mechine. As a result, the precipitate phases in the alloys were the finest when the Nd content was 1% compared the alloys with the Nd content were 2% and 3%, the size of precipitation phases are between 1-2um and there are phases like Mg2Ca，Al2Ca，and MgZn2in the alloys. After extrusion, recrystallization microstructures were found in the alloys. The tensile strengths are between 400-450MPa and the yield strengths are between 350-370MPa respectively as the differences content of Nd in the alloys after heat treatment.

scholarly journals Microstructure Changes and Improvement in the Mechanical Properties of As-Cast AlSi7MgCu0.5 Alloy Induced by the Heat Treatment and ECAP Technique at Room Temperature

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Miloš Matvija ◽  
Martin Fujda ◽  
Ondrej Milkovič ◽  
Marek Vojtko ◽  
Róbert Kočiško ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Room Temperature ◽  
Cast Alloy ◽  
Artificial Ageing ◽  
Angular Pressing ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Alloy State ◽  
Eutectic Si

The changes in the microstructure and improvement in the mechanical properties of as-cast AlSi7MgCu0.5 alloy induced by the heat treatment and technique of equal channel angular pressing (ECAP) were investigated. The heat treatment of as-cast alloy performed before the ECAP technique was required to increase the plasticity of the alloy. Therefore, the samples of analysed alloys were solution annealed at optimized temperature of 823 K for 4 hours to dissolve the particles of intermetallicπ(Al8FeMg3Si6) phase and to spheroidize the Si particles. Subsequently, water quenching and artificial ageing at optimized temperature of 573 K for 5 hours was used to obtain an overaged alloy state. The microstructure of alloy was consisted ofα(Al) solid solution, eutectic Si particles, and intermetallicβ(Mg2Si), Q-Al4Mg5Si4Cu,α-Al12(Fe,Mn)3Si, and/orα-Al15(Fe,Mn)3Si2phase particles. The crystal structure of present phases was confirmed by hard X-ray diffraction at Deutsches Elektronen-Synchrotron (DESY) in Hamburg and by the selected area electron diffraction (SAED) performed inside the transmission electron microscope (TEM). The heat-treated alloy was processed by ECAP at room temperature following route A. Repetitive ECAP of alloy homogenized the heterogeneous as-cast microstructure and formed the ultrafine subgrain microstructure with elongated subgrains of 0.2 µm in width and 0.65 µm in length and the high dislocation density. Microstructural changes in alloy induced by both heat treatment and ECAP led to the high strain hardening of the alloy that appeared in an improvement in strength, ductility, and microhardness of alloy in comparison with as-cast alloy state.

Effect of Partitioning of Quenching-Partitioning-Tempering Process on Microstructures and Hardness in High Carbon Steels

2012 ◽  
Vol 538-541 ◽  
pp. 1053-1056
Author(s):  
Yang Zheng Zeng ◽  
Kai Ming Wu ◽  
Feng Hu ◽  
Hua Zheng
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Retained Austenite ◽  
Carbon Steels ◽  
High Carbon ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Electron

The effect of partitioning process of quenching-partitioning-tempering (Q-P-T) process on hardness and microstructure were investigated. The 1-step Q-P-T and 2-step Q-P-T heat treatment were designed and carried out. The microstructure and carbides were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) patterns. Results showed that compared with 1-step Q-P-T heat treatment, more amount of retained austenite was obtained by 2-step Q-P-T heat treatment, however, the carbides were bigger in size and the hardness was lower.

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