Ambient- to Elevated-Temperature Fracture and Fatigue Properties of Mo-Si-B Alloys: Role of Microstructure
نویسندگان
چکیده
Ambientto elevated-temperature fracture and fatigue-crack growth results are presented for five MoMo3Si-Mo5SiB2–containing -Mo matrix (17 to 49 vol pct) alloys, which are compared to results for intermetallic-matrix alloys with similar compositions. By increasing the -Mo volume fraction, ductility, or microstructural coarseness, or by using a continuous -Mo matrix, it was found that improved fracture and fatigue properties are achieved by promoting the active toughening mechanisms, specifically crack trapping and crack bridging by the -Mo phase. Crack-initiation fracture toughness values increased from 5 to 12 MPa with increasing -Mo content from 17 to 49 vol pct, and fracture toughness values rose with crack extension, ranging from 8.5 to 21 MPa at ambient temperatures. Fatigue thresholds benefited similarly from more -Mo phase, and the fracture and fatigue resistance was improved for all alloys tested at 1300 °C, the latter effects being attributed to improved ductility of the -Mo phase at elevated temperatures. 1m 1m
منابع مشابه
Role of Microstructure in Promoting Fracture and Fatigue Resistance in Mo-Si-B Alloys
An investigation of how microstructural features affect the fracture and fatigue properties of a promising class of high temperature Mo-Si-B based alloys is presented. Fracture toughness and fatigue-crack growth properties are measured at 25o and 1300oC for five Mo-Mo3Si-Mo5SiB2 containing alloys produced by powder metallurgy with α-Mo matrices. Results are compared with previous studies on int...
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