微合金化对U-Co金属玻璃形成能力的影响

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

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。

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 amorphous 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 of U-Co alloy, 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.