微合金化对U-Co金属玻璃形成能力的影响

U-Co系具有较宽非晶成分区间,但其玻璃形成能力(GFA)较差。针对该体系的U_(69.2)Co_(30.8)合金,选择不同类型的元素M(M=Sn,Si,Be,Cu,Pd,Y,Zr)进行微合金化,采用铜辊甩带方法制备U_(69)Co_(30)M_1非晶合金条带样品,结合X射线衍射与差示扫描量热技术研究了微合金化对合金GFA的影响。结果表明,Sn添加对U-Co合金的GFA具有明显改善作用,Si次之,Be、Cu影响不大,Pd、Y、Zr起到恶化效果。结合合金熔化行为的改变和GFA与M元素的熔点、电负性、原子尺寸及M-C混合焓等参数的关联性分析,初步揭示出微合金化对U-Co合金GFA的影响机制,其本质应该与改变合金液体稳定性和晶化驱动力有关。

Effect of Minor Alloying on the Glass Forming Ability of U-Co Alloy

Minor alloying is a useful approach for promoting glass forming ability (GFA) of metallic glasses. U-Co metallic glasses can be achieved in a wide composition range, but their GFAs are very poor. This study is aimed to increase the GFA in U-Co system by minor alloying. Sn, Si, Be, Cu, Pd, Y and Zr were selected as different-typed minor alloying elements in U69.2Co30.8 alloy. The glassy U69Co30M1 (M=Sn, Si, Be, Cu, Pd, Y, Zr) ribbon samples were prepared by melt-spinning with a copper roller, and their phase formation and thermodynamics were investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. The results indicate that, Sn element significantly improves the GFA, Si displays the second improvement, Be and Cu are slightly effective while Pd, Y and Zr deteriorate the GFA. Based on the combination of the melting behavior change reflected by the DSC result, and the relationship between the GFA and the melting temperatures, electro-negativities, atomic sizes of M elements as well as mixing-enthalpies of M-C, the effect of the minor alloying on the GFA in U-Co system should be attributed to the variation of both metallic liquid stability and the crystallization driving force.