科研信息化技术与应用
科研信息化技術與應用
과연신식화기술여응용
E-science Technology & Application
2013年
5期
35-41
,共7页
并行计算%原子模拟%钛合金%界面
併行計算%原子模擬%鈦閤金%界麵
병행계산%원자모의%태합금%계면
parallel computation%atomistic simulation%titanium alloy%interface
界面对钛合金的力学性能有至关重要的影响。界面行为的原子模拟涉及的原子数目庞大，必须借助大规模并行计算。本研究组开发了大规模并行分子动力学程序，并将其应用于钛合金中不同种类界面行为的模拟研究。本文以钛铝金属间化合物中的孪晶界和α钛中的特殊大角晶界为例，介绍研究组在钛合金晶界行为的计算模拟方面的近期研究成果。所模拟的体系尺寸达到微米级，所需 CPU 核数几十至几百不等。研究发现，钛铝模拟晶胞沿伪孪晶方向剪切变形时，等静压力下可产生 L11结构的伪孪晶形核长大，而等静张力下剪切可产生真孪晶的形核长大，提出钛铝中一种新的孪晶长大机制。在α钛中，特定取向的两个晶粒所形成的晶界与位错发生相互作用，裂纹形核依赖于加载外力的取向而发生在晶界处或硬取向晶粒内，从而可能导致疲劳断裂行为与加载取向相关。这些结果有助于理解钛合金的塑性变形行为，并为更高尺度的模拟研究提供了原子尺度细节。
界麵對鈦閤金的力學性能有至關重要的影響。界麵行為的原子模擬涉及的原子數目龐大，必鬚藉助大規模併行計算。本研究組開髮瞭大規模併行分子動力學程序，併將其應用于鈦閤金中不同種類界麵行為的模擬研究。本文以鈦鋁金屬間化閤物中的孿晶界和α鈦中的特殊大角晶界為例，介紹研究組在鈦閤金晶界行為的計算模擬方麵的近期研究成果。所模擬的體繫呎吋達到微米級，所需 CPU 覈數幾十至幾百不等。研究髮現，鈦鋁模擬晶胞沿偽孿晶方嚮剪切變形時，等靜壓力下可產生 L11結構的偽孿晶形覈長大，而等靜張力下剪切可產生真孿晶的形覈長大，提齣鈦鋁中一種新的孿晶長大機製。在α鈦中，特定取嚮的兩箇晶粒所形成的晶界與位錯髮生相互作用，裂紋形覈依賴于加載外力的取嚮而髮生在晶界處或硬取嚮晶粒內，從而可能導緻疲勞斷裂行為與加載取嚮相關。這些結果有助于理解鈦閤金的塑性變形行為，併為更高呎度的模擬研究提供瞭原子呎度細節。
계면대태합금적역학성능유지관중요적영향。계면행위적원자모의섭급적원자수목방대，필수차조대규모병행계산。본연구조개발료대규모병행분자동역학정서，병장기응용우태합금중불동충류계면행위적모의연구。본문이태려금속간화합물중적련정계화α태중적특수대각정계위례，개소연구조재태합금정계행위적계산모의방면적근기연구성과。소모의적체계척촌체도미미급，소수 CPU 핵수궤십지궤백불등。연구발현，태려모의정포연위련정방향전절변형시，등정압력하가산생 L11결구적위련정형핵장대，이등정장력하전절가산생진련정적형핵장대，제출태려중일충신적련정장대궤제。재α태중，특정취향적량개정립소형성적정계여위착발생상호작용，렬문형핵의뢰우가재외력적취향이발생재정계처혹경취향정립내，종이가능도치피로단렬행위여가재취향상관。저사결과유조우리해태합금적소성변형행위，병위경고척도적모의연구제공료원자척도세절。
The mechanical behavior of titanium alloys is often inlfuenced signiifcantly by interfaces. The atomistic investigation of interfaces corresponds with large numbers of atoms, hence requiring large-scale parallel simulations. A molecular dynamics code for such simulations is developed in our group, and used in the investigations of interfacial behaviors in titanium alloys. The present paper introduces our recent works on the simulations of interfacial behaviors in titanium alloys, with the coherent twin boundary in TiAl and a special large-angle grain boundary inα-titanium as two examples. The size of the simulated cells is around micrometers, using tens to hundreds of CPU cores. It is found that, in TiAl under shear along the pseudo-twin direction, pseudo-twin and true twin nucleates and grows under hydrostatic compression and tension respectively. In α-Ti, the grain boundary between two grains with special orientations interacts with incoming dislocations, and depending on the orientation of the external loading, crack may nucleate either at the grain boundary or in the hard grain, thus it may cause the dependence of fracture on the orientation of external loading. These results contribute to understanding the plastic behavior of titanium alloys and provide atomic details for higher-scale simulations.
