(上海交通大學(xué) 材料科學(xué)與工程學(xué)院, 上海 200030)
摘 要: 電弧熔煉制備的(Mo0.85Nb0.15)Si2合金為MoSi2(C11b結(jié)構(gòu))和NbSi2(C40結(jié)構(gòu))兩相組織。 以電弧熔煉得到的合金為母合金， 通過光學(xué)懸浮區(qū)域熔煉法，選擇適當(dāng)?shù)纳L速度4 mm/h制備了(Mo0.85Nb0.15)Si2單晶，單晶結(jié)構(gòu)為C40結(jié)構(gòu)。 對單晶在1 200～1 700 °C進(jìn)行不同時間的退火處理。研究了不同熱處理制度對合金顯微結(jié)構(gòu)的影響規(guī)律。 結(jié)果表明： 經(jīng)1600 °C， 6 h退火處理后， 在合金中形成了排列緊密、 方向取向相同的全片層狀結(jié)構(gòu)，片層間距為200～300 nm。 經(jīng)EDS分析， 這種片層結(jié)構(gòu)由貧Nb的C11b相和富Nb的C40相組成。
關(guān)鍵字: Mo-Si系; 單晶; 金屬間化合物; 退火; 顯微結(jié)構(gòu)
(Mo0.85Nb0.15)Si2 single crystal
（ School of Materials Science and Engineering,
Shanghai Jiaotong University, Shanghai 200030, China）
Abstract: The intermetallics of (Mo0.85Nb0.15)Si2 with duplex C11b and C40 phases was prepared by arc-melting as the alloy used for single crystal growth. (Mo0.85Nb0.15)Si2 single crystal was then prepared by using optical floating zone melting method at a rate of 4mm/h. The crystal structure of the single crystal is C40 structure. A series of heat treatments (the treatment temperature is between 1 200-1 700 °C) were conducted on the single crystal. The effect of heat treatment on microstructure was investigated in detail. A full lamellar structure was observed after annealing at 1 600 °C for 6 h, and the lamellar spacing is between 200-300 nm. EDS analysis indicates that the lamellar structure consists of C11b phase (low Nb) and C40 phase (high Nb).
Key words: Mo-Si system; single crystal; intermetallics; annealing; microstructure
