(1. 湖南大學(xué) 材料科學(xué)與工程學(xué)院金屬材料系，長沙 410082；
2. Department of Materials Science and Engineering, The University of Tennessee,
318 Dougherty Building, Knoxville, TN 37996, USA)
摘 要: 采用V形缺口試樣，研究噴射沉積Al-Si/SiCp復(fù)合材料制動盤在25~450 ℃熱循環(huán)下的熱疲勞行為。通過金相顯微鏡和掃描電鏡觀察了復(fù)合材料的組織和熱疲勞裂紋形貌，研究熱疲勞裂紋形成與擴展機制。結(jié)果表明：熱疲勞主裂紋主要從V形缺口處萌生；在同樣的熱循環(huán)次數(shù)下，熱處理前的試樣要比熱處理后的試樣先出現(xiàn)裂紋，且裂紋擴展的速率較快；裂紋繞過Si顆粒向前擴展以及裂紋穿過Si顆粒向前擴展是裂紋與Si顆粒相互作用的主要機制；SiC顆粒與熱疲勞裂紋有明顯的交互作用。因此，改善Si相的形態(tài)和分布以及加強Al/SiC顆粒間的界面結(jié)合有利于提高熱疲勞裂紋擴展的抗力。
關(guān)鍵字: Al-Si/SiCp復(fù)合材料；熱疲勞；裂紋形成；裂紋擴展
Al-Si/SiCp composite for brake disc
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Department of Materials Science and Engineering, The University of Tennessee,
318 Dougherty Building, Knoxville, TN 37996, USA）
Abstract:The thermal fatigue (TF) crack propagation behaviors of sprayed Al-Si/SiCp was studied in the temperature range of 450 ℃ to room temperature using V-notch plate specimens. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to examine the damage mechanism of thermal fatigue. The results show that almost all the primary fatigue cracks at elevated temperatures initiate at V-notch. The crack in test sample before heat-treatment prefers to occur and the crack propagation rate is larger than that of the test sample after heat-treatment. The propagation cracking around Si particles and through Si particles are the principle mechanisms of interaction between Si particles and crack. The SiC particles play an important role in thermal fatigue cracking. Also, improving the shape and distribution of Si particles and strengthening the Al/SiC interface can improve the resistance of thermal fatigue crack of composites.
Key words: Al-Si/SiCp composite material; thermal fatigue; crack initiation; crack propagation
