Microstructure and High Temperature Mechanical Properties of Mg-1Si-1Y Alloy

2012 ◽  
Vol 268-270 ◽  
pp. 365-370 ◽  
Author(s):  
Ying Ma ◽  
Zhong Ming Zhang ◽  
Zhen Lin Lv ◽  
Chun Jie Xu

Mg-1Si alloy doped with 1%Y was prepared by in-situ reaction synthesis. The effect of hot extrusion on the microstructure and elevated-temperature mechanical properties of the alloy was studied. The microstructures were analyzed by optical microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffractometry. The results show that as-cast Mg-1Si-1Y alloy consists of dendritic α-Mg phase, eutectic needle-like Mg2Si phase and Mg24+xY5 phase precipitated from α-Mg, Mg2Si can be modified and refined by yttrium, and α-Mg grains can be refined by dynamic recrystallization occurred in hot extrusion process. The tensile strength and elongation of the alloy at ambient temperature are improved prominently by hot extrusion. The tensile strength and elongation of the extruded alloy is 185.3MPa and 24.3% at 120°C. The improved elevated-temperature properties of the alloy are ascribed to the fine-grained strengthening and dispersion strengthening from Mg2Si and Mg24+xY5 particles.

2011 ◽  
Vol 690 ◽  
pp. 339-342
Author(s):  
Katsuyoshi Kondoh ◽  
Thotsaphon Threrujirapapong ◽  
Hiroyuki Fukuda ◽  
Junko Umeda

By using light metal (Mg, Al, Ti) powders coated with un-bundled multi-wall carbon nanotubes (MWCNTs) via wet process, powder metallurgy (P/M) light metal matrix composite reinforced with un-bundled nanotubes was prepared by spark plasma sintering (SPS) and subsequently hot extrusion process. The microstructure and mechanical properties of the composites were evaluated. In the case of pure titanium, the distribution of CNTs and in-situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyzer. The mechanical properties of TMC were significantly improved by the additive of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of tensile specimens were analyzed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed. In the case of Mg-Al alloys, in-situ formation of Al2MgC2compounds at the interface between CNTs and Mg-matrix occurred and effective for the tensile transfer loading, and resulted in the increment of tensile strength of the composite material.


2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Katsuyoshi Kondoh ◽  
Thotsaphon Threrujirapapong ◽  
Hisashi Imai ◽  
Junko Umeda ◽  
Bunshi Fugetsu

By using pure titanium powder coated with unbundled multiwall carbon nanotubes (MWCNTs) via wet process, powder metallurgy (P/M) titanium matrix composite (TMC) reinforced with the CNTs was prepared by spark plasma sintering (SPS) and subsequently hot extrusion process. The microstructure and mechanical properties of P/M pure titanium and reinforced with CNTs were evaluated. The distribution of CNTs and in situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyzer. The mechanical properties of TMC were significantly improved by the additive of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of tensile specimens were analyzed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed.


2007 ◽  
Vol 534-536 ◽  
pp. 181-184
Author(s):  
Seung Hoon Yu ◽  
Kwang Seon Shin

Various reactions and the in-situ formation of new phases can occur during the mechanical alloying process. In the present study, Al powders were strengthened by AlN, using the in-situ processing technique during mechanical alloying. Differential thermal analysis and X-ray diffraction studies were carried out in order to examine the formation behavior of AlN. It was found that the precursors of AlN were formed in the Al powders and transformed to AlN at temperatures above 600oC. The hot extrusion process was utilized to consolidate the composite powders. The composite powders were canned in an Al can and then extruded at elevated temperatures. The microstructure of the extrusions was examined by SEM and TEM. In order to investigate the mechanical properties of the extrusions, compression tests and hardness measurements were carried out. It was found that the mechanical properties and the thermal stability of the Al/AlN composites were significantly greater than those of conventional Al matrix composites.


2013 ◽  
Vol 668 ◽  
pp. 823-829 ◽  
Author(s):  
Xiu Qing Zhang ◽  
Ge Chen ◽  
Yang Wang ◽  
Min Yu Han

Homogenized magnesium alloy Mg-6Zn-Si-0.25Ca has been hot-extruded and then aging treated for improving the magnesium alloy plastic deformation ability and promoting applications of magnesium alloys. In the hot extrusion process, the influences of extrusion parameters for microstructures and mechanical properties of Mg-6Zn-Si-0.25Ca magnesium alloy were investigated. The results show that dynamic recrystallization occurred during hot extrusion. Compared with as-cast alloy, the grains are fined remarkably, and the mechanical properties are enhanced obviously. Twin crystals appeared in grains after hot extrusion, with the extrusion temperature rising, twin crystal structures has been reduced. Aging further increased the mechanical properties of the estruded alloy. The ultimate tensile strength of Mg-6Zn-Si-0.25Ca alloy is about 385 MPa and the elongation is about 11% when extruded at 320°C(extrusion ratio is 10) and aged at 190°C for 8h.


2005 ◽  
Vol 475-479 ◽  
pp. 497-500
Author(s):  
Ritsuko Tsuzuki ◽  
Katsuyoshi Kondoh

Super light and high performance Mg2Si/Mg composites, which had excellent mechanical properties, were developed via the combination of solid-state synthesis and hot extrusion process. In this study, cold compacting (CP) and repeated plastic working (RPW) were firstly carried out for the mixture of Mg-Si powders, and the refinement of both Mg grains and dispersoids. Each specimen was evaluated by observation of microstructure and tensile test. As a result, it was understood that Mg2Si dispersoids were refined and dispersed into Mg matrix, and were flowed along extrusion direction. And their mechanical properties were higher than the conventional die casting alloys. Also the effect of RPW as the improvement of properties and the decrease of synthesis temperature were confirmed.


2009 ◽  
Vol 618-619 ◽  
pp. 495-499 ◽  
Author(s):  
Katsuyoshi Kondoh ◽  
Thotsaphon Threrujirapapong ◽  
Junko Umeda ◽  
Hisashi Imai ◽  
Bunshi Fugetsu

Powder metallurgy (P/M) titanium matrix composite (TMC) reinforced with multi-wall carbon nanotube (MWCNT) was prepared by spark plasma sintering (SPS) and hot extrusion process, where the powder surface was coated by un-bundled CNTs via wet process. The microstructure and mechanical properties of P/M pure titanium and reinforced with CNTs were evaluated. The distribution of CNTs and in-situ formed titanium carbide (TiC) compounds during sintering was investigated by optical and scanning electron microscopy (SEM) equipped with EDS analyser. The mechanical properties of TMC were significantly improved by adding a small amount of CNTs. For example, when employing the pure titanium composite powder coated with CNTs of 0.35 mass%, the increase of tensile strength and yield stress of the extruded TMC was 157 MPa and 169 MPa, respectively, compared to those of extruded titanium materials with no CNT additive. Fractured surfaces of specimens were analysed by SEM, and the uniform distribution of CNTs and TiC particles, being effective for the dispersion strengthening, at the surface of the TMC were obviously observed.


2013 ◽  
Vol 710 ◽  
pp. 21-24 ◽  
Author(s):  
Jian Gang Lv ◽  
Gao Feng Quan ◽  
Rui Chun Li ◽  
Chun Yuan Shi ◽  
Ying Bo Zhang ◽  
...  

According to the profile section of transport equipment, the wide and hollow AZ31 magnesium alloy profiles was self-designed. Extrusion molding performance of the profiles, the law of microstructure and mechanical properties were studied when billets pretreatment and extrusion temperature were changed. The conclusions are as follows: (1) The grains of AZ31 profiles extruded by pre-extrusion billet are smaller and the strength is better, its maximum tensile strength is 280MPa. (2) Other processes being equal, the grains of AZ31 profiles are smaller and strength is higher, but the plastic is bad, when the extrusion temperature is 300°C. However, both strength and ductility of AZ31 profiles are better, when the extrusion temperature is 350°C. (3) Wide and Hollow AZ31 profiles perform significant heterogeneity and anisotropic characteristics on mechanical properties.


2006 ◽  
Vol 114 ◽  
pp. 145-150 ◽  
Author(s):  
Pawel Widlicki ◽  
Halina Garbacz ◽  
Małgorzata Lewandowska ◽  
Wacław Pachla ◽  
Mariusz Kulczyk ◽  
...  

Hydrostatic extrusion can be viewed as one of the methods of Severe Plastic Deformation, SPD, for the fabrication of ultra-fine grained alloys which causes a significant increase in the mechanical properties such as tensile strength and hardness. In the present study the microstructure of 6082 aluminium alloy after hydrostatic extrusion was investigated. Hydroextrusion was performed in three steps with accumulated true strains of 1.34, 2.73 and 3.74 respectively. Microstructural observations were carried out using SEM, TEM and light microscopy. Grain and inclusion sizes, shapes and distribution were investigated in the HE processed samples. The study has shown that the hydrostatic extrusion process results in a profound refinement of both the grain size and the inclusions in 6082 aluminium alloy.


2017 ◽  
Vol 894 ◽  
pp. 21-24 ◽  
Author(s):  
S.Nю Ab Rahim ◽  
Mohd Amri Lajis

In the present work, aluminum AA6061 chip metals were extruded by hot extrusion and the effect of extrusion parameters on the mechanical properties and surface integrity were investigated. The objective of the present studies it to analyze the mechanical and structural properties of 6061 after plastic consolidation by hot extrusion. Tensile test results showed that material extruded using temperature 550°C exhibit higher ultimate tensile strength (UTS) compared with temperature of 400°C. Fracture surfaces shown that ductile fracture mode occurred at condition 500°C and 2 hours, and brittle fracture occurred at condition 400°C.


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