Li Xiaopeng, Zhang Zeyu, Yang Yi, Fan Jikang, Kong Jian, Wang Kehong
College of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
Materials (Basel). 2020 Aug 7;13(16):3488. doi: 10.3390/ma13163488.
Bulk metallic glasses (BMGs) are promising for multifunctional and structural application in different industries. However, the limited size of BMGs hinders their further application. The welding of BMGs has shown the possibility of getting rid of the casting size limitation. The heat-affected zone (HAZ) and fusion zone (FZ) often undergo severe crystallization during the welding process. It is still unclear whether the crystallization occurs during the heating process or the cooling process. To figure out the crystallization mechanisms of Zr-based BMGs during the electron beam welding process, the Zr-based BMGs with the composition of ZrTiCuNiBe were remelted by electron beam. The microstructures of the HAZ and the remelting zone (RZ) were analyzed. The thermal field of the electron beam welding was obtained by the finite element method (FEM). The critical conditions for crystallization during the heating and cooling processes were obtained by differential scanning calorimetry (DSC) and the Kissinger equation. The results show that the ZrTiCuNiBe in the HAZ undergoes severe crystallization, while the ZrTiCuNiBe in RZ keeps amorphous state after the remelting process. The low cooling rate in the HAZ is responsible for its crystallization.
大块金属玻璃（BMGs）在不同行业的多功能和结构应用方面前景广阔。然而，BMGs有限的尺寸阻碍了它们的进一步应用。BMGs的焊接已显示出摆脱铸造尺寸限制的可能性。在焊接过程中，热影响区（HAZ）和熔合区（FZ）常常会经历严重的结晶。目前仍不清楚结晶是在加热过程中还是冷却过程中发生。为了弄清楚基于Zr的BMGs在电子束焊接过程中的结晶机制，对成分是ZrTiCuNiBe的基于Zr的BMGs进行了电子束重熔。分析了HAZ和重熔区（RZ）的微观结构。通过有限元方法（FEM）获得了电子束焊接的热场。通过差示扫描量热法（DSC）和基辛格方程获得了加热和冷却过程中结晶的临界条件。结果表明，HAZ中的ZrTiCuNiBe经历了严重的结晶，而RZ中的ZrTiCuNiBe在重熔过程后保持非晶态。HAZ中较低的冷却速率是其结晶的原因。
