Abstract A model for the viscosity (η) of melts in the system CaMgSi2O6-CaAl2Si2O8-NaAlSi3O8 (Di-An-Ab) based on data compiled from the literature is presented. The model is calibrated on 560 measurements of melt viscosity at 1 atm pressure on 40 individual melt compositions and 303 measurements obtained at high pressure on 18 melt compositions. The model is continuous and accounts for variations in melt composition (X), temperature (T) and pressure (P). At ambient pressure, the model spans 15 orders of magnitude of η, a T range of 933–2450 K and reproduces the dataset well (RMSE = 0.26 log units). The high-P model is calibrated over a T range of 970–2470 K and pressures of 50 MPa to 13 GPa for viscosities of 10−1 to 1014.5 Pa s and reproduces the high-pressure dataset to within (larger) experimental uncertainties (RMSE = 0.35 log units). Used in conjunction with chemical proxies for melt structural organization (i.e. SM and NBO/T), the model illustrates the strong coupling between viscosity and changes in melt polymerization as a function of X and P. Di-An-Ab melts with SM values >25.34 have positive pressure coefficients and show a minimal to strong increase in viscosity with pressure. Model values of glass transition temperatures (Tg) (i.e. η ~ 1012 Pa s) range between 930 K and 1130 K at 1 atm; Tg values for highly polymerized melts are depressed by as much as 150 K at 5 GPa at elevated pressures but are higher for more depolymerized melts and higher P. Melt fragility (m) is only weakly affected by increased P expressed by a slight decrease in m for the most fragile melts versus a slight increase for the least fragile melts. Activation energies (Ea) increase with rising P for depolymerized melts and decrease with rising P for polymerized melts with the crossover at SM = 25.34. Ea values increase at low T for all P conditions and the effects of P are most pronounced at lower T. Lastly, a comparison of the liquidus surface topology for the ternary system to the corresponding isokoms of viscosity shows the relative effects of composition and temperature on melt viscosity at liquidus conditions to be highly varied.

中文翻译：

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Di-An-Ab 系统中熔体粘度的温度-压力-成分模型

摘要 基于文献汇编的数据，提出了系统 CaMgSi2O6-CaAl2Si2O8-NaAlSi3O8 (Di-An-Ab) 中熔体的粘度 (η) 模型。该模型在 1 个大气压下对 40 种单独熔体组合物的 560 次熔体粘度测量值和在高压下对 18 种熔体组合物进行的 303 次测量值进行校准。该模型是连续的，并考虑了熔体成分 (X)、温度 (T) 和压力 (P) 的变化。在环境压力下，模型跨越 15 个数量级的 η，T 范围为 933-2450 K，并很好地再现了数据集（RMSE = 0.26 log 单位）。高压模型在 970-2470 K 的 T 范围和 50 MPa 至 13 GPa 的压力下针对 10-1 至 1014.5 Pa s 的粘度进行校准，并将高压数据集复制到（更大）实验不确定性 (RMSE = 0.35 对数单位）。与熔体结构组织的化学代理（即 SM 和 NBO/T）结合使用，该模型说明了粘度与作为 X 和 P 函数的熔体聚合变化之间的强耦合。具有 SM 值的 Di-An-Ab 熔体 > 25.34 具有正压力系数，并显示粘度随压力的增加从极小到极强。玻璃化转变温度 (Tg)（即 η ~ 1012 Pa s）的模型值在 1 个大气压下介于 930 K 和 1130 K 之间；高聚合熔体的 Tg 值在 5 GPa 和高压下降低多达 150 K，但对于更多解聚熔体和更高的 P 值更高。熔体脆性 (m) 仅受 P 增加的微弱影响，表现为 m 的轻微下降对于最脆弱的熔体，相对于最不脆弱的熔体略有增加。活化能 (Ea) 随解聚熔体的 P 升高而增加，而聚合熔体的活化能 (Ea) 随 P 升高而降低，在 SM = 25.34 处有交叉。对于所有 P 条件，Ea 值在低 T 下增加，并且 P 的影响在较低 T 时最显着。 最后，三元体系的液相线表面拓扑与相应的粘度等距线的比较显示了成分和温度对液相线条件下的熔体粘度变化很大。