scholarly journals Tungsten-Based Metallic Glasses with High Crystallization Temperature, High Modulus and High Hardness

2005 ◽  
Vol 46 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Madoka Ohtsuki ◽  
Kyoko Nagata ◽  
Ryuji Tamura ◽  
Shin Takeuchi
Keyword(s):  
Metallic Glasses ◽  
Crystallization Temperature ◽  
High Hardness ◽  
High Modulus ◽  
High Crystallization ◽  
High Crystallization Temperature

Evaluation of Mo-based Amorphous Alloy Thin Films Exhibiting High Crystallization Temperature

2005 ◽  
Vol 894 ◽  
Author(s):  
Junpei Sakurai ◽  
Seiichi Hata ◽  
Ryusuke Yamauchi ◽  
Akira Shimokohbe
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Amorphous Alloy ◽  
Crystallization Temperature ◽  
Alloy Composition ◽  
Phase Distribution ◽  
Amorphous State ◽  
Al Alloy ◽  
High Crystallization ◽  
High Crystallization Temperature

AbstractThis paper presents the characteristics of Mo-based (Mo-Zr based) amorphous alloys exhibiting a high crystallization temperature. In order to investigate the alloy composition showing an amorphous state in the Mo-Zr-X (X=Si and Al) alloy system, thin film libraries were prepared at first by combinatorial arc plasma deposition (CAPD). The composition region corresponding to the amorphous state was identified in the libraries with X-ray diffraction. On the basis of the alloy composition and phase distribution of the thin film libraries, additional amorphous Mo-Zr-Si and Mo-Zr-Al thin films were prepared by a carousel sputtering system. The crystallization temperature Tc of the amorphous Mo50Zr(50-x)Six thin films exceeded 1073 K. However, the Mo-Zr-Si thin films were so brittle that they could not be subjected to tensile testing. In the Mo-Zr-Al thin films, Tc of the Mo-rich MoxZr(90-x)Al10 and MoxZr(76-x)Al24 thin films exceeded 973 K. Although the toughness of Mo-based amorphous alloy thin films could be improved slightly by adding Al, the amorphous Mo-Zr-Al thin films were also brittle.

Improved electrical and material characteristics of HfTaO gate dielectrics with high crystallization temperature

2005 ◽  
Vol 87 (23) ◽  
pp. 232901 ◽  
Author(s):  
M. H. Zhang ◽  
S. J. Rhee ◽  
C. Y. Kang ◽  
C. H. Choi ◽  
M. S. Akbar ◽  
...  
Keyword(s):  
Crystallization Temperature ◽  
Gate Dielectrics ◽  
Material Characteristics ◽  
High Crystallization ◽  
High Crystallization Temperature

scholarly journals A Novel Bioactive Glass Containing Therapeutic Ions with Enhanced Biocompatibility

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4600 ◽  
Author(s):  
Rachele Sergi ◽  
Devis Bellucci ◽  
Roberta Salvatori ◽  
Alexandre Anesi ◽  
Valeria Cannillo
Keyword(s):  
Bioactive Glass ◽  
Dissolution Rate ◽  
Crystallization Temperature ◽  
Biological Properties ◽  
Thermal Treatments ◽  
Cellular Viability ◽  
In Vitro Bioactivity ◽  
High Crystallization ◽  
High Crystallization Temperature

A novel bioactive glass containing therapeutic ions with enhanced biocompatibility was designed and produced by the classical melt-quenching route. Starting from a very promising composition (Bio_MS), which combined bioactivity and high crystallization temperature, the ratio between some oxides was tailored to obtain a new and more reactive (in terms of dissolution rate) bioactive glass, called BGMSN (composition in mol%: 6.1 Na2O, 31.3 CaO, 5 MgO, 10 SrO, 2.6 P2O5, 45 SiO2). The aim of this work was to produce a bioactive glass with a good biological performance, preserving, at the same time, the high crystallization temperature achieved for Bio_MS; this is strategic in order to avoid undesired crystalline phases during thermal treatments, which can undermine the bioactivity and even the stability of final products. A complete characterization of the novel bioactive glass was performed in terms of thermal, mechanical and biological properties and in vitro bioactivity. The thermal behavior of the bioactive glass was studied by heating microscopy, differential thermal analysis (DTA) and optical dilatometry; BGMSN showed a very high crystallization temperature and a high sinterability parameter, thus being suitable for applications where thermal treatments are required, such as sintered samples, coatings and scaffolds. Mechanical properties were investigated by the micro-indentation technique. The in vitro biological properties were evaluated by means of both direct and indirect cell tests, i.e., neutral red (NR) uptake and MTT assay, using murine long bone osteocyte Y4 (MLO-Y4) cells: the cellular viability of BGMSN was higher compared to cellular viability of 45S5, both in direct and indirect tests. Finally, the in vitro bioactivity test by soaking samples in simulated body fluid (SBF) showed high dissolution rate, with a good rate of formation of hydroxyapatite.

scholarly journals Additive Manufacturing of Bulk Metallic Glasses—Process, Challenges and Properties: A Review

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1279
Author(s):  
Navid Sohrabi ◽  
Jamasp Jhabvala ◽  
Roland E. Logé
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Metallic Glasses ◽  
Small Volume ◽  
Review Paper ◽  
Bulk Metallic Glasses ◽  
Amorphous State ◽  
High Hardness ◽  
Complete Understanding ◽  
High Cooling Rates

Bulk Metallic Glasses (BMG) are metallic alloys that have the ability to solidify in an amorphous state. BMGs show enhanced properties, for instance, high hardness, strength, and excellent corrosion and wear resistance. BMGs produced by conventional methods are limited in size due to the high cooling rates required to avoid crystallization and the associated detrimental mechanical properties. Additive manufacturing (AM) techniques are a potential solution to this problem as the interaction between the heat source, e.g., laser, and the feedstock, e.g., powder, is short and confined to a small volume. However, producing amorphous parts with AM techniques with mechanical properties comparable to as-cast samples remains a challenge for most BMGs, and a complete understanding of the crystallization mechanisms is missing. This review paper tries to cover recent progress in this field and develop a thorough understanding of the correlation between different aspects of the topic. The following subjects are addressed: (i) AM techniques used for the fabrication of BMGs, (ii) particular BMGs used in AM, (iii) specific challenges in AM of BMGs such as the control of defects and crystallization, (iv) process optimization of mechanical properties, and (v) future trends.

scholarly journals A Conflict of Fineness and Stability: Platinum- and Palladium-Based Bulk Metallic Glasses for Jewellery

2020 ◽  
Author(s):  
O. S. Houghton ◽  
A. L. Greer
Keyword(s):  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Precious Metals ◽  
High Hardness ◽  
Scratch Resistance ◽  
Cast State ◽  
High Definition ◽  
Glass Forming ◽  
Thermoplastic Forming ◽  
Near Net Shape

For the metals used in jewellery, high hardness and the associated scratch resistance are much sought after. Conventional crystalline alloys for jewellery are alloyed and extensively processed (thermally and mechanically) to improve hardness, but it is difficult to reach values beyond 300 HV. The advent of bulk metallic glasses, based on precious metals and with hardness exceeding 300 HV in the as-cast state, is therefore of great interest for both jewellery and watchmaking. The non-crystalline structure of these materials not only gives high hardness, but also the opportunity to shape metals like plastics, via thermoplastic forming. For more traditional jewellery manufacture, bulk metallic glasses also exhibit high-definition and near-net-shape casting. Gold-based alloys have long dominated the consideration of bulk metallic glasses for jewellery as they can comply with 18K hallmarks. Although bulk metallic glasses based on platinum or palladium possess excellent thermoplastic formability, and are without known tarnishing problems, achieving useful glass-forming ability within the more restrictive hallmarking standards typically used for jewellery (≥95 wt.% Pt or Pd) is, at best, challenging. In this review, platinum- and palladium-based bulk metallic glasses are discussed, focusing on their potential application in jewellery and on the further research that is necessary.

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