Thermal Tempering of Bulk Metallic Glasses

2002 ◽  
Vol 754 ◽  
Author(s):  
Cahit C. Aydiner ◽  
Ersan Üstündag
Keyword(s):  
Metallic Glasses ◽  
Casting Process ◽  
Glass Forming Ability ◽  
Stress Generation ◽  
Copper Mold ◽  
Glass Forming ◽  
Viscoelastic Models ◽  
Compressive Stresses ◽  
Thermal Tempering ◽  
Stress Profiles

ABSTRACTThe recent development of multi-component alloys with exceptional glass forming ability has allowed the processing of large amorphous metal samples. The possibility of formation of thermal tempering stresses during the processing of these bulk metallic glass (BMG) specimens was investigated using the (1) instant freezing, and (2) viscoelastic models. Both models yielded similar results although from vastly different approaches. It was shown that fast convective cooling of Zr41.2Ti13.8Cu12.5Ni10Be22.5 plates could generate significant compressive stresses on the surfaces balanced with mid-plane tension. The crack compliance method was then employed to measure the stress profiles in a BMG plate that was cast in a copper mold. These profiles were roughly parabolic suggesting that thermal tempering was indeed the dominant residual stress generation mechanism. However, the magnitude of the measured stresses (with peak values of only about 1.5% of the yield strength) was significantly lower than the modeling predictions. Possible reasons for this discrepancy are described in relation to the actual casting process and material properties.

Effect of B2O3 Fluxing on Glass-Forming Ability and Soft Magnetic Properties of Fe(-Co)-B-Si-Nb Bulk Metallic Glasses

2014 ◽  
Vol 783-786 ◽  
pp. 1895-1900 ◽  
Author(s):  
Teruo Bitoh
Keyword(s):  
Magnetic Properties ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Glass Forming Ability ◽  
The Other ◽  
Maximum Diameter ◽  
Soft Magnetic Properties ◽  
Copper Mold ◽  
Soft Magnetic ◽  
Glass Forming

The effect of B2O3 fluxing on the glass-forming ability (GFA), the structure and the soft magnetic properties of Fe (-Co)-B-Si-Nb bulk metallic glasses (BMGs) has been investigated. The large Fe-Co-B-Si-Nb BMG specimens with diameters up to 7.7 mm, which is approximately 1.5 times as large as that of the maximum diameter of the copper mold cast one (= 5 mm), were prepared by the fluxing and water quenching. Thus the GFA of the Fe-Co-B-Si-Nb BMG are improved by the fluxing. It was confirmed that the soft magnetic properties of the Fe-Co-B-Si-Nb BMG are also improved by the fluxing. On the other hand, it was found for the Co-free Fe-B-Si-Nb BMG that the B2O3 fluxing promotes the precipitation of the α-Fe (-Si) and Fe2B phases in the central region of the specimens; i.e., the GFA of the Fe-B-Si-Nb BMG is decreased by the fluxing. The Fe-B-Si-Nb BMG specimens show a flat hysteresis loop, indicating a good linear relationship between the magnetic induction and the applied magnetic field. These results of the Fe-B-Si-Nb BMG show that it is possible to develop a new soft magnetic material that exhibits constant permeability, which is necessary for producing inductors and choke coils.

Effect of Minor Si and Ag Additions on Glass-Forming Ability of Ti-Cu-Co-Zr-Sn-Be Bulk Metallic Glass

2011 ◽  
Vol 688 ◽  
pp. 400-406
Author(s):  
Xin Fang Zhang ◽  
Hong Xiang Li ◽  
Zhi Qiang Jiang ◽  
Seong Hoon Yi
Keyword(s):  
Metallic Glass ◽  
Metallic Glasses ◽  
Base Alloy ◽  
Maximum Size ◽  
Amorphous Structure ◽  
Glass Forming Ability ◽  
Copper Mold ◽  
Glass Forming ◽  
Splat Quenching ◽  
Ag Additions

Effect of Minor Si and Ag additions on glass-forming ability (GFA) of the base Ti44Cu38.9Co4Zr6Sn2Be5.1(at. %) alloy are studied. (Ti44Cu38.9Co4Zr6Sn2Be5.1)100-xRx(R = Si, Ag, x=0, 1, 2, 3 at. %) metallic glasses are formed by splat-quenching and copper mold suction casting. It is found that the minor Si and Ag additions enhance the glass-forming ability of Ti44Cu38.9Co4Zr6Sn2Be5.1greatly. The maximum size of fully amorphous structure is increased from 4 mm for base alloy to be larger than 6 mm for alloys containing 1-2 at. % Si/Ag, while Si/Ag more than 2 at. % additions decrease the GFA.

Understanding the Glass-forming Ability of Cu50Zr50 Alloys in Terms of a Metastable Eutectic

2005 ◽  
Vol 20 (9) ◽  
pp. 2307-2313 ◽  
Author(s):  
W.H. Wang ◽  
J.J. Lewandowski ◽  
A.L. Greer
Keyword(s):  
Metallic Glasses ◽  
Glass Formation ◽  
Composition Range ◽  
Intermetallic Phase ◽  
Glass Forming Ability ◽  
Copper Mold ◽  
Wide Composition Range ◽  
Glass Forming ◽  
Copper Mold Casting ◽  
Mold Casting

Interest in finding binary alloys that can form bulk metallic glasses has stimulated recent work on the Cu–Zr system, which is known to show glass formation over a wide composition range. This work focuses on copper mold casting of Cu50Zr50 (at.%), and it is shown that fully amorphous rods up to 2-mm diameter can be obtained. The primary intermetallic phase competing with glass formation on cooling is identified, and the glass-forming ability is interpreted in terms of a metastable eutectic involving this phase. Minor additions of aluminum increase the glass-forming ability: with addition of 4 at.% Al to Cu50Zr50, rods of at least 5-mm diameter can be cast fully amorphous. The improvement of glass-forming ability is related to suppression of the primary intermetallic phase.

Cu−Zr−Ti ternary bulk metallic glasses correlated with (L → Cu8Zr3 + Cu10Zr7) univariant eutectic reaction

2008 ◽  
Vol 23 (5) ◽  
pp. 1249-1257 ◽  
Author(s):  
Chun-Li Dai ◽  
Jing-Wei Deng ◽  
Ze-Xiu Zhang ◽  
Jian Xu
Keyword(s):  
Glass Transition ◽  
Metallic Glasses ◽  
Eutectic Reaction ◽  
Glass Forming Ability ◽  
Compositional Dependence ◽  
Copper Mold ◽  
Glass Forming ◽  
Copper Mold Casting ◽  
Mold Casting ◽  
Ti Content

Starting from Cu60Zr30Ti10, the compositional dependence of bulk metallic glass (BMG) formation was revisited in the Cu−Zr−Ti ternary system. It was revealed that the optimal BMG-forming composition is located at Cu60Zr33Ti7, for which a monolithic BMG rod 4 mm in diameter can be fabricated using copper mold casting. This composition is along, although slightly off, the univariant eutectic groove for the reaction (L → Cu8Zr3 + Cu10Zr7). With respect to the corresponding Cu−Zr binary alloys, Ti has a significant effect on further stabilizing the liquid, thus increasing the glass-forming ability. For the Cu60Zr40−yTiy (3 ⩽ y ⩽ 10) series BMGs, the glass transition temperature Tg decreased with increasing Ti content, at a rate of about 2.8 K/at.%. Among these BMGs, significant compositional dependence of compressive plasticity is not observed, irrespective of the Tg change. Cu60Zr33Ti7 glass exhibits maximum fracture strength around 2160 MPa.

Effects of High Co Contents in Fe-Cr-Mo-C-B-Y Alloy on the Glass Forming and the Mechanical Properties

2013 ◽  
Vol 652-654 ◽  
pp. 1054-1058 ◽  
Author(s):  
Qing Jun Chen ◽  
Jiang Lie Liu ◽  
Xian Liang Zhou ◽  
Jun Shen ◽  
Xiao Zhen Hua
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Metallic Glasses ◽  
Amorphous Region ◽  
Glass Forming Ability ◽  
Copper Mold ◽  
Casting Method ◽  
Glass Forming ◽  
Wedge Shape

A series of wedge shape Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) samples were prepared by copper mold suction casting method. The effects of high Co contents on glass forming ability (GFA) and mechanical properties of Fe24+XCo24-X Cr15Mo14C15B6Y2 bulk metallic glasses (BMG) were investigated, respectively. The glass forming ability of bulk amorphous Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) and Fe41Co7Cr15Mo14C15B6Y2 alloys have been researched. Simultaneously, the thermal conductivity parameters of those alloys were tested. The maximum thickness of amorphous region of wedge-shaped samples are dm =7.80 mm for Fe28Co20Cr15Mo14C15B6Y2, dm =7.10 mm for Fe41Co7Cr15Mo14C15B6Y2 and the thermal conductivity are λ=7.11 w.m-1.k-1 and 7.19 w.m-1.k-1, the thermal diffusivity are α=1.875 mm2/s and 1.905 mm2/s for Fe28Co20Cr15Mo14C15B6Y2 and Fe41Co7Cr15Mo14C15B6Y2 BMGs, respectively. The glass forming ability of Fe28Co20Cr15Mo14C15B6Y2 alloy is bigger than that of well known Fe41Co7Cr15Mo14C15B6Y2 alloy. With the change of Co content, the Vickers hardness of Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) change from 1292 to 1322Hv.

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