The Influence of Compositional Changes on the Glass-Forming Ability of Y-Containing Mg Alloys
- PDF / 1,935,754 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 22 Downloads / 173 Views
The Influence of Compositional Changes on the Glass-Forming Ability of Y-Containing Mg Alloys E. Eshed1,2, M. Bamberger1, A. Katsman1 1 2
Department of Materials Science and Engineering, Technion, Haifa 32000, Israel Israel Institute of Metals, Technion, Haifa 32000, Israel
ABSTRACT The effect of compositional changes on the glass forming ability of Mg alloys containing Y was studied. Four rapidly-solidified Mg-alloys were investigated: Mg91Y7.5La1.5, Mg85Y12La3, Mg86Y9.5Cu2.5La2 and Mg82Y11La4Eu3. XRD and DSC spectra revealed that the Mg86Y9.5Cu2.5La2 was the most amorphous out of the investigated alloys. A model based on a spinodal-like decomposition of a supercooled liquid alloy was developed. The model provides qualitative and quantitative explanation for the variation in glass forming ability. INTRODUCTION Magnesium alloys have been of great interest in recent decades due to their very low specific weight. However, their wide-spread use remains hindered by the relatively low mechanical properties and low corrosion resistance they possess. One possible way to overcome these downsides and still benefit from the low specific weight of magnesium is to manufacture magnesium alloys in their amorphous state. Amorphous alloys are known to have higher corrosion and wear resistance and better mechanical properties as compared to their crystalline counterparts [1-4]. Most researchers dealing with amorphization of magnesium alloys have been focused on the highly glass-formable Mg65Cu25Y10 alloy having a pronounced glass transition around 140ºC, and a highly exothermic crystallization point around 200ºC [4-6]. Although the Mg65Cu25Y10 alloy and its variants have excellent glass forming ability (GFA), they have also several drawbacks such as a relatively high specific weight (3-4 g/cm3) and low workability and ductility below the glass transition temperature, high potential for developing micro-galvanic corrosion upon dynamic crystallization [2,6-8]. Finding new highly glass-formable Mg-based compositions remains a challenging task since the precise relations between the physical and thermodynamic properties of an alloy and its GFA remains mostly unknown. In the present work, the Y and La containing Mg-alloys were investigated for their GFA. The main goal of the present work was to investigate the influence of compositional changes within the chosen alloy system and to formulate a model that will explain this influence and allow prediction of the GFA of other Mg alloys. EXPERIMENTAL As-cast ingots of four alloys: Mg91Y7.5La1.5, Mg85Y12La3, Mg86Y9.5Cu2.5La2 and Mg82Y11La4Eu3 were prepared from the corresponding pure metals (all of which had purity of over 99.9%) excluding Y which was introduced using an -Mg24Y5 master-alloy ingot. The alloying of all compositions was performed in a SiC crucible placed in an electric furnace under constant HFC-134a/CO2 gas mixture atmosphere. Upon the completion of alloying the liquid metal in the SiC crucible was allowed to cool slowly in air. All alloys weighed between 100 and 200 grams.
Data Loading...
