Cu基块状非晶晶化过程的微区变形及力学性能

Deformation and mechanical properties of Cu-based bulk metallic glasses during crystallization

在玻璃转变温度以下选择350、400、475及600 K进行1 h的等温退火,用纳米压痕仪、扫描电镜等研究Cu基块状非晶晶化过程的力学性能及变形。Cu基块状非晶在纳米压头作用下体现弹-塑性变形方式,载荷—位移曲线和压痕周边多重剪切带的特征证明了塑性变形的存在。350 K退火试样具有较大的压痕硬度HV和弹性模量E值及较小的塑性变形量dn值;400 K退火后,HV和E值显著减小,dn值明显增大;475 K退火后,有少量晶体相析出,但合金以非晶的特性为主,HV和E值继续减小,dn值继续增大;600 K退火后,晶体相进一步长大和析出,其固溶强化和弥散强化使合金的HV和E值有所增加,dn值略有减小。对塑性变形机理进行了初步分析。

350, 400, 475 and 600 K below glass transition temperature were chosen for isothermal annealing for 1 h. Mechanical properties and deformation of Cu-based bulk metallic glasses（BMGs） during crystallization were studied with nanoindentation instrument and scanning electron microscope（SEM）. The results indicate Cu-based BMGs deform in elastic-plastic modes under a nanoindenter. Load-displacement curve and multiple shear bands around a nanoindenter confLrm the existence of plastic deformation. The sample annealed at 350 K exhibits higher microhardness（HV）, elastic modulus（E）, and lower plastic deformation（d.）; HV and E values decrease and dn value increases significantly at 400 K; crystal phases exist at 475 K, but the major properties of the alloy is amorphous. HV and E values reduce and d. value increases continually; with growth and precipitation of crystal phases at 600 K, solid solution strengthening and dispersion strengthening of the phases slightly augment HV and E values, and reduce d. value. The plastic deformation mechanism during crystallization is preliminarily analyzed.