The densification of a powder mixture containing titanium diboride and 20 wt.% molybdenum disilicide during nonisothermal spark plasma sintering was experimentally studied. The sintering process was assisted with an external pressure of 50.93 MPa in vacuum at a controlled constant heating rate of 1.67 and 2.72 K per second. It was established that sintering occurred when the thermodynamic temperature reached 1155 K, which should be taken as the critical brittle–ductile transition temperature for molybdenum disilicide, a less refractory material. The densification kinetics was analyzed using the continuum theory for bulk viscous flow of a porous body, considering the effect of powder particle shape on the rheological properties of the sintered body. In general, the sintering process was characterized by a decrease in the root-mean-square stress within the porous body matrix to the limiting zero value as it approached the nonporous state and by an increase in the root-mean-square strain rate along the curve with a maximum. Computational modeling of the densification kinetics for the powder composite, involving determination of the activation energy for viscous flow of the composite matrix as a function of temperature and root-mean-square stress, allowed the initial, low-temperature, and medium-temperature stages of spark plasma sintering to be identified. At the initial stage up to 1220 K, the activation energy increased nonlinearly and sharply, which can be caused by active spark flashes with the formation of plasma within the loose random packing of the powder particles, as a similar stage is not observed in conventional pressure assisted sintering. At the next low-temperature temperature stage, the activation energy increased as the root-mean square stress decreased. In the temperature range from 1300 to 1389 K, the activation energy for viscous linear flow of the composite matrix was 223 kJ/mol. In the medium-temperature range from 1414 to 1485 K, the activation energy increased to 255 kJ/mol.

对含有二硼化钛和 20 wt.% 二硅化钼的粉末混合物在非等温放电等离子烧结过程中的致密化进行了实验研究。烧结过程在真空中以 50.93 MPa 的外部压力以每秒 1.67 和 2.72 K 的受控恒定加热速率辅助。确定当热力学温度达到1155 K时发生烧结，该温度应作为二硅化钼这种难熔材料的临界脆塑转变温度。利用多孔体整体粘性流的连续介质理论分析致密化动力学，考虑粉末颗粒形状对烧结体流变性能的影响。一般来说，烧结过程的特征是，当接近无孔状态时，多孔体基体内的均方根应力降低至极限零值，并且沿均方根应变率增加。具有最大值的曲线。粉末复合材料致密化动力学的计算模型，包括确定复合基体粘性流动的活化能作为温度和均方根应力的函数，允许初始、低温和中温阶段放电等离子烧结的性能待鉴定。在高达 1220 K 的初始阶段，活化能非线性且急剧增加，这可能是由于松散随机堆积的粉末颗粒内形成等离子体而引起的主动火花闪光，而在常规压力下未观察到类似的阶段辅助烧结。在接下来的低温阶段，活化能随着均方根应力的减小而增加。在1300~1389 K温度范围内，复合基体粘性线性流动的活化能为223 kJ/mol。在1414至1485 K的中温范围内，活化能增加至255 kJ/mol。