Room Temperature Brittlement of T2 in the Mo-Si-B System
作者单位：State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing
会议名称：《中国材料大会2012》
会议日期：2012年
学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）]
基 金：supported by National Natural Science Foundation of China (No.50871012) National Key Basic Research Program of China (No.2011CB605502)
关 键 词：T2 Intrinsic brittlement First-principles calculation Covalent bond
摘 要：Compression and three-point bending tests were conducted at room temperature （RM） on the Mo5SiB2 （T2） alloy, which was prepared by sparking plasma sintering （SPS）. It was found that almost no plastic deformation occured in the T2 alloy before failure but with a tremendous compressive strength of 2907 MPa. The fracture toughness determined from the single edge notch bend specimen is 3.34 MPa·m1/2 , similar to the value of 3.5 MPa·m1/2 in ɑ-Al2O3 . Once the cleavage crack initiated near the notch under continuous loads, it propagated on a certain plane （001） until the specimen completely fractured. In this work, the electronic structure was also calculated by the first-principles method, indicating that the contribution to RM brittleness is mainly caused by the covalent bonds which arrange alternately in the T2 phase.