摘要
通过研究Cu-Hf-Ti三元合金的玻璃形成能力对合金成分的依赖性,优化出Cu_(56)Hf_(27)Ti_(17)和Cu_(57)Hf_(27)Ti_(16)合金,其形成金属玻璃棒材的临界直径为5 mm.采用单边缺口试样测量的Cu_(26)Hf_(27)Ti_(17)金属玻璃的缺口韧性KQ为(92±10)MPa·m^(1/2),几乎是Cu_(49)Hf_(42)Al_9金属玻璃(K_Q=(56±9)MPa·m^(1/2))的一倍,是目前所知韧性最高的铜基块体金属玻璃.相对于Cu_(49)Hf_(42)Al_9金属玻璃,Cu_(56)Hf_(27)Ti_(17)金属玻璃的高韧性与其高Poisson比(v=0.361)和低剪切模量(G=38.6 GPa)关联.Cu_(56)Hf_(27)Ti_(17)块体金属玻璃的高韧性表现为裂纹尖端形成大塑性区,在裂纹萌生与扩展过程中,形成大尺寸剪切滑移区和脉纹花样区.Cu_(56)Hf_(27)Ti_(17)和Cu_(49)Hf_(42)Al_9块体金属玻璃在缺口韧性上的差异表明,从Cu-Zr/Hf基合金中去除Al元素有利于金属玻璃的韧化.
As a sort of quasi brittle materials, fracture toughness of bulk metallic glasses （BMGs） is of paramount importance for their engineering application. Among the BMG families, Cu-based BMGs are of interest due to their low cost, high strength and less brittleness. As indicated in previ- ous work, the Cu49Hf42Al9 BMG exhibits a good combination of toughness and glass forming ability （GFA）. Moreover, toughness of BMG significantly depends on alloy composition. In the Zr Cu-Al system, it was suggested that increasing the Al content in the alloy does not favor to the plasticity of the glass. Then, it is expected that Al-free Cu-Hf-Ti BMGs may be tougher than the Cu49Hf42Al9 BMG. In addition, notched cylindrical samples were used for the toughness assessment in previous investigation, which probably introduce an overestimation in toughness in comparison with archival data of engineering materials. To obtain the glassy plate samples for toughness measurements to meet the ASTM E399 requirement, alloys with robust GFA is necessary. In this work, the composition dependence of GFA for ternary Cu Hf-Ti alloys was revisited. The alloys with the optimal GFA are located around the Cu56Hf27Ti17 and Cu57Hf27Ti16. The critical diameter to form the BMG rods was determined to be 5 mm. Then, the Cu56Hf27Ti17 BMG plates of 2.5 mm in thickness can be fabricated as the specimens for toughness assessments. Using the single-edge notched specimen for three point bending test, the notch toughness KQ of Cu56Hf27Ti17 BMG was determined to be （92±10） MPa.mI/2. It is nearly doubled with respect to the Cu49Hf42Al9 BMG （KQ=（56±9） MPa.mU2）. It means that the Cu56Hf27Ti17 BMG is the toughest among currently-available Cu-based BMGs. Such high tough- ness of Cu56Hf27Ti17 BMG also correlates with its moderate Poisson＇s ratio （v=0.361） and low shearmodulus （G=38.6 GPa）. The enhanced toughness of CusaHf27Ti17 BMG is associated with the ex- tended plastic zone size at the notch tip with the proliferation of shear banding e
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第8期969-975,共7页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目51171180~~
关键词
铜合金
金属玻璃
断裂韧性
弹性常数
Cu alloy, metallic glass, fracture toughness, elastic constant
