顯微組織演變
( 1. 西安交通大學(xué) 材料科學(xué)與工程學(xué)院
金屬材料強(qiáng)度國家重點(diǎn)實(shí)驗(yàn)室， 西安 710049；
2. 西安建筑科技大學(xué) 材料科學(xué)與工程學(xué)院，
西安 710055)
摘 要: 用燃燒波淬熄法研究了TiC-Ni金屬陶瓷自蔓延高溫合成（SHS）中的組織演變， 淬熄試樣中保留了未反應(yīng)區(qū)、反應(yīng)區(qū)和已反應(yīng)區(qū)。 用掃描電子顯微鏡觀察了燃燒反應(yīng)中顯微組織的轉(zhuǎn)變過程， 用能譜儀分析了各微區(qū)的成分變化， 測量了燃燒溫度Tc和燃燒波蔓延速度， 并用XRD分析了反應(yīng)產(chǎn)物的相組成。 結(jié)果表明， TiC-Ni金屬陶瓷自蔓延高溫合成（SHS）的機(jī)理為溶解-析出機(jī)制， 鎳粉與鈦粉的固態(tài)擴(kuò)散導(dǎo)致低熔點(diǎn)Ti-Ni溶液形成， Ti、 Ni、 C粉粒逐漸向Ti-Ni溶液中溶解， 當(dāng)Ti-Ni-C溶液中的Ti和C濃度飽和時， 從中析出TiC顆粒， 同時形成粘結(jié)TiC顆粒的Ni↓3Ti基體。分析結(jié)果表明， 該體系的燃燒合成具有不完全性， 最終產(chǎn)物中殘留少量Ni3Ti2＋NiTi共晶體， 這種反應(yīng)的不完全性是由于使用了較粗的Ti粉和Ni粉。
關(guān)鍵字: TiC-Ni；金屬陶瓷； 自蔓延高溫合成； 組織演變
high-temperature synthesis of TiC-Ni cermet
GU Mei-zhuan1， JIN Zhi-hao1
（ 1. State Key Laboratory for Mechanical Behavior of Materials,School of Materials Science and Engineering, Xi′an Jiaotong University,
Xi′an 710049, China;
2. Department of Materials Science and Engineering,
Xi′an University of Architecture and Technology, Xi′an 710055, China）
Abstract: The microstructural evolution during self-propagating high-temperature synthesis (SHS) of TiC-Ni cermet was studied by means of the combustion front quenching method. The process of microstructure conversion in the quenched sample was observed using a scanning electron microscope (SEM), a compositional change in each micro-region of the microstructure was studied by energy dispersive X-ray (EDX), the temperature and the velocity of combustion reaction were measured. The results show that the mechanism of combustion synthesis of TiC-Ni composition can be described as dissolution-preciptation. Ti-Ni melt is formed through solid diffusion between titanium and nickel powders, then the atoms of Ti, C and Ni gradually dissolve into the Ti-Ni melt, and TiC particles will prepicitate from the Ti-Ni-C melt as the Ti-Ni-C melt is saturated, at the same time, the Ni3Ti matrix forms, which binds the TiC particles. In addition, the results show that the combustion synthesis is possibly incompleteness because of coarser Ti and Ni powders used in the combustion synthesis, a small amount of eutectic, (Ni3Ti2+NiTi) is found in the final product. This incompleteness of the combustion reaction is attributed to using coarser Ti and Ni powders in the combustion synthesis.
Key words: TiC-Ni； cermet； self-propagating high-temperature synthesis； microstructural evolution
