Microstructure and strengthening mechanism of Si₃N₄/Invar joint brazed with TiN_p-doped filler

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• 作者：Tianpeng Wang^a ; Chunfeng Liu^a ; Christian Leinenbach^b ; Jie Zhang^a ; ^{hitzhangjie@hit.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Si3N4 ceramic ; Invar alloy ; Brazing ; Composite filler ; Nanoindentation
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：5 January 2016
• 年：2016
• 卷：650
• 期：Complete
• 页码：469-477
• 全文大小：4202 K

文摘

Ag–Cu–Ti+TiNp composite filler was developed to braze Si₃N₄ ceramic to Invar alloy, and subsequently the effect of TiNp content on the microstructure and mechanical properties of the joints was investigated. The typical microstructure of the brazed joints is Si₃N₄/TiN+Ti₂N+TiSi+Fe₂Ti/Ag(s.s)+Cu(s.s)+TiNp/wavelike Fe₂Ti+Ni₃Ti/Ag–Cu eutectic/Invar alloy. With the increase of TiNp content, the reaction layers near the Si₃N₄ become thinner, and Ag–Cu eutectic appears less and finer between the ceramic and wavelike intermetallics. The maximum shear strength increases from 63 MPa to 229 MPa with the optimum TiNp content of 2 vol%, compared with the case without TiNp. The hardness and elastic modulus of the reaction phases were characterized by nanoindentation to reveal the strengthen of brazing seam. The following reasons are believed to strengthen the brazed joint: the thermal expansion coefficient (CTE) reduction of the composite filler, appropriate thickness of the Si₃N₄/braze reaction layer, the strengthen of the braze.