含Er钴基非晶合金的力学性能及热稳定性研究

钴基非晶合金具有高强度、高硬度、高弹性模量、低损耗、高磁导率等优势，是一种理想的结构与磁性功能材料，具有广阔的应用前景。然而，由于其非晶形成能力较低，同时缺乏对其力学与热力学性能的数据和研究，其大规模应用受到严重限制。在此背景下，本文基于前人的研究，选取高非晶形成能力、高强度的CoFeCrMoCBEr体系为研究对象，开展合理的成分设计，筛选出较优异的基础成分，并在其基础上通过调整Fe-C比进一步提高其强度，利用差示扫描量热法研究了该成分非晶合金的热稳定性。

首先，制备了三种成分的Co-Fe-Cr-Mo-C-B-Erx（x=1.5,2,2.5）系非晶合金，其中Co43Fe5Cr15Mo14C15B6Er2 BMG展现出最高的压缩强度（3.46 GPa）以及最宽的过冷液相区间，因此被确定为优异的基础成分。其断裂模式为由光滑镜区向外放射状的剪切带导致的脆性断裂，丰富的剪切带扩展是导致非晶合金高强度的一个重要因素，缺陷将引起剪切转变的严重局域化。

其次，在Co43Fe5Cr15Mo14C15B6Er2 BMG的基础上通过调整Fe-C原子比获得了更高强度的非晶合金，当Fe元素含量为6 at.%时合金的压缩强度最高，达到4.06 GPa，相比Co43Fe5Cr15Mo14C15B6Er2 BMG提高了约17%。断裂方式为层状刚性撕裂导致的脆性断裂，局部脉状花样说明了塑性变形被明显局域化，同时亦有互相平行的纳米波纹产生，这与非晶合金弹性变形阶段的变形行为有关，也是对应极度脆性金属玻璃断裂的显著结构特征。

最后，对Co基非晶合金的热稳定性进行了研究，发现随着加热速率的增大Co基非晶合金的玻璃化转变温度、晶化温度、晶化峰值温度均增大，利用Kissinger方程计算了晶化激活能约为372.9 kJ/mol；当等温退火温度为867 K时其晶化孕育时间约为12 mins，说明此体系非晶在过冷液相区具有较强的抵抗晶化能力，即具有较优异的热稳定性。

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