玻璃态Cu29Zr32Ti15Al5Ni19在纳米压入过程中的压痕尺寸效应及应变硬化现象

Indentation size effects and strain hardening of glassy Cu29Zr32Ti15Al5Ni19 during nanoindentation

摘要:

利用纳米压痕技术对高熵非晶合金Cu₂₉Zr₃₂Ti₁₅Al₅Ni₁₉分别在载荷控制模式、连续刚度模式和循环加载模式下进行了研究。该合金在纳米压入过程中会发生Pop-in现象,且载荷大小比加载速率对Pop-in现象的影响更大。当载荷超过40mN时,即使采用高达5mN/s的加载速率仍然可以观察到Pop-in现象。该合金存在压痕尺寸效应,其测试纳米硬度随载荷的增大而下降,其Meyer指数(n)小于2。压入过程中的能量耗散分数(E_d)在54%-60%之间变化。循环加载测试结果显示该合金加工硬化效应明显。

Abstract:

A high entropy bulk metallic glass (HE-BMG) Cu₂₉Zr₃₂Ti₁₅Al₅Ni₁₉ was investigated by nanoindentation in detail with load-controlled, continuous stiffness measurement (CSM) and cyclic loading mode, respectively. Pop-in occurs in this alloy during nanoindentation. Applied load have more influences on the pop-in events than loading rate does. When the applied load is larger than 40mN, obvious pop-in events can be observed in the loading curves even at high up to 5mN/s loading rate. Indentation size effect exists in this alloy, confirmed by the hardness decreasing with the increasing indentation load and a Meyer’s index n less than 2. The fraction of energy dissipated during indentation (E_d) changes within the range of 54%-60%. Cyclic loading tests reveal obvious hardening effect.