中文摘要：

分析了载荷对Mo_5SiB_2合金压痕裂纹影响规律,观察了压痕裂纹形貌特征,表征了裂纹长度与载荷的关系,确定了压痕裂纹系统,选取不同的压痕方程计算了室温断裂韧性KIC值,探讨了压痕载荷以及压痕方程对KIC值的影响关系。结果表明,Mo_5SiB_2合金压痕裂纹系统属于中位裂纹,只要选择合适的压痕方程,载荷并不影响断裂韧性值。压痕法测定Mo_5SiB_2合金断裂韧性合适的经验方程为KIC=0.8193H~（0.5）E~（0.5）a~2c~（-1.5）,测得的其KIC值为2.63 MPa·m~（1/2）。

英文摘要：

The influence of load for indentation crack of Mo_5SiB_2alloy was analyzed,the morphology characteristics of indentation crack was observed,the relationship between crack length and load was characterized.Then the indentation crack system was determined,and different indentation equations were selected to calculate the fracture toughness KICvalue of the alloy at room temperature.The relationship of indentation load and indentation equations on KICvalue was discussed.The results show that indentation crack of the Mo_5SiB_2alloy is in line with the median crack under this experimental conditions,the load does not affect fracture toughness as long as the appropriate indentation equation is used.Empirical equation of M-3（ KIC= 0.8193H~（0.5）E~（0.5）a~2c~（-1.5）） is suitable for calculating KICvalue of the Mo_5SiB_2alloy and the value is 2.63 MPa·m~（1/2）.