摘要
测定了Hi-Nicalon SiC纤维在惰性气氛下高温热处理后的断裂强度,并对其强度进行了Weibull分布统计分析,通过SEM研究了温度变化对Hi-Nicalon SiC纤维表面形貌和力学性能的影响,着重分析了Hi-Nicalon SiC纤维的裂纹扩展机制及断裂机理。研究表明,在惰性气氛保护下其强度随退火温度的升高而下降,且经过1800℃长时间(10h)退火后的Hi-Nicalon SiC纤维基体转为晶态,断裂模式也就从非晶态的脆性断裂转变为晶态材料的解理断裂。经统计分析,纤维表面部分活性氧化造成的结构缺陷可忽略,断裂源主要集中在纤维内部,惰性气氛下纤维强度下降主要是由解理断裂作用的结果。
Hi-Nicalon silicon carbide fibers were annealed at 1400 ℃, 1600 ℃ and 1800 ℃ for 10 h in argon atmosphere, respectively. The strength of fibers was determined by monofilament tensile testing machine. The tensile strength was statistically analyzed with Weibull distribution and the fracture surfaces of the fibers were observed by SEM. The results indicate that the strength of the fibers obeys Weibull distribution, and the tensile strength decreases with the increase of annealing temperatures. After being annealed at 1800 ℃ for 10 h, the specimens show cleavage fracture. Statistical analysis reveals that the defects in fibers＇ surface have negligible effect on their strength, most of cracks initiate at the inner region of fibers, and the specimens show brittle/flat fracture.
出处
《金属热处理》
EI
CAS
CSCD
北大核心
2007年第8期55-58,共4页
Heat Treatment of Metals
基金
国家自然科学基金重点项目(编号50532010)
西北工业大学凝固技术国家重点实验室开放课题资助项目
