(嘉應(yīng)學(xué)院物理與光信息科技學(xué)院，梅州 514015)
摘 要: 采用分子動(dòng)力學(xué)方法和Quantum Sutton-Chen多體勢(shì)，對(duì)2萬(wàn)個(gè)液態(tài)金屬銅(Cu)原子在兩個(gè)不同冷速凝固過(guò)程中其微觀團(tuán)簇結(jié)構(gòu)的形成特性以及晶體的成核生長(zhǎng)進(jìn)行模擬。運(yùn)用雙體分布函數(shù)、Honeycutt-Andersen(HA)鍵型指數(shù)法、原子團(tuán)類(lèi)型指數(shù)法(CTIM-2)和可視化分析等方法，對(duì)凝固過(guò)程中微觀結(jié)構(gòu)轉(zhuǎn)變和原子團(tuán)簇的微觀結(jié)構(gòu)演變特性進(jìn)行分析。結(jié)果表明：冷卻速率為4.0×1012 K/s和2.0×1012K/s時(shí)，系統(tǒng)形成以1421、1422鍵型或由這兩種鍵型構(gòu)成的面心立方(FCC)(12 0 0 0 12 0)和六角密集(HCP)基本原子團(tuán)(12 0 0 0 6 6)為主體的晶體結(jié)構(gòu)；尤其是由1421鍵型構(gòu)成的面心立方(12 0 0 0 12 0)基本原子團(tuán)在晶體生長(zhǎng)和對(duì)微觀結(jié)構(gòu)演變的影響占主導(dǎo)地位。兩種冷卻速度下的結(jié)晶溫度分別為673K和773K，即冷卻速度越慢，結(jié)晶溫度越高；系統(tǒng)最終形成了由FCC和HCP組成的混合晶體結(jié)構(gòu)，但以FCC晶體結(jié)構(gòu)為主；FCC(12 0 0 0 12 0)基本原子團(tuán)在慢速低溫時(shí)具有較好的遺傳特性，基本原子團(tuán)之間很容易連接在一起構(gòu)成較大的納米級(jí)大團(tuán)簇結(jié)構(gòu)。
關(guān)鍵字: 液態(tài)金屬Cu；分子動(dòng)力學(xué)模擬；Q-SC多體勢(shì)；微觀結(jié)構(gòu)演變；成核；生長(zhǎng)
（School of Physics and Optical Information Sciences, Jiaying University, Meizhou 514015, China）
Abstract:A simulation study was performed on the formation properties of micro-cluster structures and nucleation and growth of crystals during solidification process of 20000 liquid metal Cu atoms at two different cooling rates by adopting the molecular dynamics method and Quantum Sutton-Chen multi-body potential.The pair distribution function,the bond-type index method of Honeycutt-Andersen(HA),cluster-type index method(CTIM-2)and visualization analysis were used to analyze and study the transition of microstructures and evolution properties of micro-cluster configurations during solidification process. The results show that the crystal structures form mainly with the 1421 and 1422 bond-types or the FCC(12 0 0 0 12 0) basic cluster, and the HCP(12 0 0 0 6 6)basic cluster being composed of the two bond-types at the cooling rates of 4.0×1012K/s and 2.0×1012K/s.Especially, the FCC(12 0 0 0 12 0) basic clusters consisting of 1421 bond-type occupy a dominant position in crystal-growth and the effect of microstructures evolution. Meanwhile,it has been found that the temperatures of crystallization are 673K and 773K under two cooling rates,respectively. Namely,the lower the cooling speed is, the higher the crystal temperature is, and finally the system forms the crystal and amorphous mixed coexistence structures of FCC ad HCP,but the FCC crystal structures is major. When the cooling rates and temperature are lower, the FCC(12 0 0 0 12 0)basic cluster posseses better genetic characteristic, and the basic clusters are easier to form bigger nano-cluster structure by bonding together.
Key words: liquid metal Cu; molecular dynamics simulation; Q-SC multi-body potential; microstructure evolution; nucleation; growth
