Microstructure Evolution of Mg-6Zn-6Al Magnesium Alloy during Semi-Solid Partial Remelting

2011 ◽  
Vol 306-307 ◽  
pp. 608-612
Author(s):  
Xiao Feng Huang ◽  
K. Feng ◽  
Y. Ma ◽  
F.Y Yan ◽  
Ti Jun Chen
Keyword(s):  
Solid State ◽  
Magnesium Alloy ◽  
Shape Factor ◽  
Solid Particles ◽  
Dendritic Microstructure ◽  
Partial Remelting ◽  
Semi Solid ◽  
Average Size ◽  
Microstructure Of The Material ◽  
Holding Temperature

A new magnesium alloy, named as Mg-6Zn-6Al(ZA66), using for thixoforming production has been developed. The microstructure of the material during partial remelting holding in the semi-solid state was characterized. The results indicate that non-dendrite microstructure in ZA66 magnesium alloy billets can be obtained, but the proper partial remelting temperature and holding time should be select. After being treated at 575°Cfor 20 min, the ZA66 alloys can obtain a non-dendritic microstructure with finer unmelted primary solid particles (37 μm) and shape factor about 0.6. With the increasing holding temperature from 575°C to 590°C,the average size of unmelted primary solid particles increases and globular tendency becomes more obvious.

Study on Partial Remelting Microstructures and Mechanical Properties of ZK60-RE Magnesium Alloy

2006 ◽  
Vol 116-117 ◽  
pp. 279-283
Author(s):  
Wei Wei Shan ◽  
Zhi Ming Du ◽  
Shou Jing Luo
Keyword(s):  
Mechanical Properties ◽  
Solid State ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Equal Channel Angular Extrusion ◽  
High Strength ◽  
High Quality ◽  
Partial Remelting ◽  
Semi Solid ◽  
Re Elements

ZK60-RE is a kind of high strength magnesium alloy. Here, starting materials are casting ZK60-RE magnesium alloy and ZK60-RE magnesium alloy extruded by equal channel angular extrusion (ECAE), reheating to semi-solid state and studied on their partial remelting microstructures by means of microscope. The results show that ZK60-RE magnesium alloy extruded by ECAE are much finer and lead to the formation of spheroids quite rapidly while RE elements modified casting need a little longer time. At the same time, the mechanical properties of two kinds of ZK60-RE magnesium alloys are given. To do that, we want to find better magnesium alloys with high mechanical properties and good thixotropy, which adapt to semi-solid process to form the high quality complex component one time.

Study on Microstructural Evolution of Deformed Magnesium Alloy during Partial Remelting

2012 ◽  
Vol 192-193 ◽  
pp. 246-250 ◽  
Author(s):  
Qiang Chen ◽  
Gao Zhan Zhao ◽  
Da Yu Shu
Keyword(s):  
Solid State ◽  
Magnesium Alloy ◽  
Microstructural Evolution ◽  
Eutectic Phase ◽  
Holding Time ◽  
Mg Alloy ◽  
Liquid Droplets ◽  
Grain Coarsening ◽  
Partial Remelting ◽  
Semi Solid

Microstructural evolution of ZK60 Mg alloy during partial remelting was investigated in this paper. The results show that ZK60 Mg alloy semi-solid billets were successfully produced by recrystallisation and partial remelting (RAP) process. Following partial remelting in each case, grain coarsening had occurred in the semi-solid state with increasing holding time. Liquid was present, during partial remelting all four temperatures, in the form of isolated intragranular droplets. These liquid droplets were produced by intragranular eutectic phase and entrapped liquid. Intragranular liquid droplets migrated and merged into some large rounded liquid droplets. After the spheroidization was completed, coarsening and coalescence occurred. When temperature is relatively low (the thickness of liquid is relatively thin), grains contacted with each other, which produced irregular-shaped grains.

Formation Mechanism of Thixotropic Microstructure of AM60 Alloy during Solidification

2014 ◽  
Vol 1030-1032 ◽  
pp. 86-89
Author(s):  
Bo Xing
Keyword(s):  
Formation Mechanism ◽  
Solid Substrate ◽  
Research Field ◽  
Primary Phase ◽  
Solid Particles ◽  
Metallographic Analysis ◽  
Semisolid Slurry ◽  
Dendritic Microstructure ◽  
Quenching Method ◽  
Semi Solid

A research field on semi-solid metal processing is the preparation of semi-solid slurry with non-dendritic microstructure. Nowadays, with the technological innovation of semi-solid slurry preparation, people turn to produce the non-dendritic semisolid microstructure by locally cooling of the alloy melt during solidification. Therefore, it is necessary to investigate the formation mechanism of the non-dendritic microstructure formation because the primary phase undergoes a specially controlled nucleation and growth which distinctly different from the commom solidification. In this paper, the semisolid slurry of AM60 alloy was produced by Self-Inoculation Method (SIM), and the microstructure evolution of primary α-Mg was investigated by water quenching method and metallographic analysis. The results indicate that the semisolid microstructure of AM60 alloy produced by SIM composed of small and globular α-Mg particles, and these grains undergone a coarsing process during quiescent holding. The solid substrate caused by the fusion of solid particles and the dendritic fragments caused by melt flow caused the grain multiplication, and then the grain undergone a steadily growth because of the uniform temperature distribution, resulting in the increase of grains density and a small grain size of the AM60 semisolid slurry.

Microstructural evolution of an ECAE-formed ZK60-RE magnesium alloy in the semi-solid state

2009 ◽  
Vol 506 (1-2) ◽  
pp. 8-15 ◽  
Author(s):  
Zude Zhao ◽  
Qiang Chen ◽  
Yanbin Wang ◽  
Dayu Shu
Keyword(s):  
Solid State ◽  
Magnesium Alloy ◽  
Microstructural Evolution ◽  
Semi Solid

Development of Adapted Heat Treatments for Steels out of the Semi-Solid State after Thixoforming

2008 ◽  
Vol 141-143 ◽  
pp. 695-700 ◽  
Author(s):  
Sebastian Dziallach ◽  
Wolfgang Püttgen ◽  
Wolfgang Bleck
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid State ◽  
Treatment Strategies ◽  
Solid Particles ◽  
High Wear Resistance ◽  
Hard Material ◽  
Current State ◽  
Suitable Heat Treatment ◽  
Semi Solid

The process of thixoforming incorporates a series of forming processes in the semi-solid state, which can be categorized between the conventional processes of forging and casting and combines the advantages of these processes. Thixoforming of steels in the semi-solid state, requires round, solid particles (globulites) in a liquid matrix which is deformed with low forming forces. In order to achieve laminar material flow and to produce segregation-free components, the material must fulfil diverse criteria. First, the melting interval should be as large as possible for an easy temperature regulation. Next, low solidus and liquidus temperatures are advantageous regarding tool loading. Additionally, thixoformable steels should show a melting behaviour that is finegrained and globular. Furthermore, these steels should possess low contents of intraglobular liquid phase fractions. This paper gives a survey of the current state of steel Thixoforming and deals with the development of adaptive heat treatment strategies. Regarding the structure formation and the development of suitable heat treatment strategies, the once semi-solid state yields new structures that can be applied in ways not previously possible with conventional hardening processes. New microstructures and up to date unknown better mechanical properties can be adjusted with an optimised heat treatment strategy. By this, new fields of application for thixo-materials can be entered and also advanced procedures for special applications can be established. For example the steel X210CrW12 leads to a very hard material with high wear-resistance, which can be used at higher temperatures than the conventional hardened material. In general, new generic microstructures after thixoforming results in unexpected favourable mechanical properties. Problems arise with respect to segregation and pores which resulting in inhomogeneous property distributions.

Casting in the Semi-Solid State of ZK60 Magnesium Alloy Modified with Rare Earth Addition

2014 ◽  
Vol 922 ◽  
pp. 694-699 ◽  
Author(s):  
E.P. Silva ◽  
Larissa Fernandes Batista ◽  
Bruna Callegari ◽  
Ivan Feierabend ◽  
Ricardo Henrique Buzolin ◽  
...  
Keyword(s):  
Solid State ◽  
Magnesium Alloy ◽  
Cast Alloy ◽  
Casting Process ◽  
Aged Alloy ◽  
Mechanical Agitation ◽  
Solution Treated ◽  
Homogeneous Chemical ◽  
Semi Solid ◽  
Zk60 Magnesium Alloy

In this work, the casting process under mechanical agitation in the semi-solid state was investigated for the production of ZK60 magnesium alloy modified with the addition of 2.5% wt ofmischmetal. The results show that this process enables the production of ingots with homogeneous chemical composition and free of shrinkage, inner defects and internal oxidation. The as-cast microstructure consists of an α-Mg matrix with globular grains reinforced by a grid of distinct intermetallics of Mg-Zn, Mg-Zn-RE and Mg-RE type along the grain boundaries. The yield strength at room temperature undergoes more than 50% increase during direct T5 aging, thus reaching 170 MPa. At 300°C, however, the dispersion of nanometric precipitates does not modify the hot deformation behavior of the aged alloy, which undergoes dynamic recrystallization in a similar manner to the as-cast alloy. DRX at 300°C is fastest for the alloy solution-treated at 500°C.

Development of New Type Semi-Solid Injection Process for Magnesium Alloy

2014 ◽  
Vol 217-218 ◽  
pp. 361-365
Author(s):  
Yuichiro Murakami ◽  
Kenji Miwa ◽  
Naoki Omura ◽  
Shuji Tada
Keyword(s):  
Magnesium Alloy ◽  
Volume Fraction ◽  
Solid Particles ◽  
Casting Defects ◽  
Microstructure Observation ◽  
Injection Process ◽  
Fraction Solid ◽  
The Matrix ◽  
New Type ◽  
Semi Solid

We have developed new type semi-solid injection process for magnesium alloy. This process does not require to use any cover gases and the special magnesium billet such as thixo-billet. In this study, plate specimens were produced by injecting the semi-solid billet with different fraction solid. The microstructure observation, detection of casting defects by an X-ray computed tomography scanner, and tensile test were carried out. With increasing fraction solid, the size and shape of α-Mg solid particles became smaller and more spherical. In the condition of low fraction solid or forming in liquid state, the casting defects were located in the center of the specimen at the thickness direction. Additionally, the volume fraction of the casting defect decreased with increasing fraction solid. Moreover, the casting defects can be reduced by preventing solidifying and clogging of the top of the nozzle. Then, the specimen which has few casting defects could be obtained by injecting the slurry of fraction solid 0.5. However, the tensile strength and yield strength were highest in fraction solid 0.4. It is contemplated that the composition of the solid solution component element in the matrix was increased in fraction solid of 50%, therefore the matrix became brittle.

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