【作者】 张新宇；

【导师】 王文魁； 刘日平；

【作者基本信息】 燕山大学 ， 材料学， 2004， 硕士

【摘要】 本文利用同步辐射光源、金刚石对顶砧和多砧大压机设备分别研究了室温和高温条件下不同组分硅锗合金在高压下的压缩行为、相变反应和凝固等问题。 高压原位同步辐射实验研究表明,Si₅₀Ge₅₀ 合金在 0～8.7GPa 的压力范围内的状态方程可表示为: -（ΔV/V）-192789P-902072×10^-1P²+2.4213×10^-1P³-2.062×10^-2P⁴氩弧炉熔炼的 Si₅₀Ge₅₀ 合金样品因存在一定量的缺陷,在 0～1.5GPa压力范围内,体积压缩变化明显,且包含非弹性压缩形变;压力升高时,在 1.5～8.7GPa 范围内,体积变化率随压力变化较小,产生结构强化。 通过对比实验发现,Si₅₀Ge₅₀ 合金在金刚石对顶砧中金刚石立方结构到β-Sn 结构的转变压力低于多砧压机中的值。主要原因是金刚石对顶砧实验样品中存在的剪切应力促进金刚石立方结构到β-Sn 结构的转变。 通过研究 Si_100-xGe_x 合金样品金刚石立方结构至β-Sn 结构相变时的压力值 PT 与成分 X 的关系,发现 Si_100-xGe_x 合金随 Si 含量的增加 PT 值增大,但 PT与成分 X 并不符合简单的线性关系。 利用多砧压机设备结合同步辐射 X 射线衍射方法,进行了不同压力下硅锗合金的高压凝固实验。确定在 9GPa 至 9.5GPa 压力之间存在一个临界值,压力高于此临界值时,熔态硅锗合金凝固过程中首先固化为β-Sn 结构相,然后β-Sn 结构相转化为 ST-12 结构。压力低于此临界值时,熔态硅锗合金凝固时,直接固化为金刚石立方结构相。 关键词 硅锗合金;同步辐射;压致相变;高压凝固更多还原

【Abstract】 Compression behavior, phase transition and solidification of various component Si-Ge alloys at room and high temperature under high pressure were studied by synchrotron radiation source, diamond anvil cell and multi-anvil press apparatus. The effect of pressure on compression behavior of Si₅₀Ge₅₀ alloy has been studied by in situ synchrotron radiation high pressure technique. The equation of state for Si₅₀Ge₅₀ alloy in the range of 0 to 8.7GPa pressure can be expressed as: -（ΔV/V）-192789P-902072×10^-1P²+2.4213×10^-1P³-2.062×10^-2P⁴Volume compression changes were obvious and containing non-elasticitic deformation in the range of 0 to 1.5GPa because of the existence of defects in the samples melted in an argon arc furnace. With increasing pressure, volume change rate varied slowly to pressure, and structure strengthening was generated in the range of 1.5 to 8.7GPa. The critical pressure PT at which the cubic diamond structure in Si₅₀Ge₅₀ alloy transited toβ-Sn structure within a diamond anvil cell was lower then that in the multi-anvil press. The main reason is that the shear stress existing in the diamond anvil cell favored the phase transition from cubic diamond structure toβ-Sn structure. PT value increased with the Si content in Si_100-xGe_x alloys. But PT was not in a simple linear relationship with X. Solidification experiments of Si-Ge alloys under various pressures were carried out using the multi-anvil press and the synchrotron radiation X ray technique. An critical pressure, around 9 to 9.5GPa was determined. Higher than this pressure, the Si-Ge melt solidified into β-Sn structure first, and then transited to ST-12 structure. Lower than this pressure, the Si-Ge melt solidified into cubic diamond structure directly.更多还原