Component Shape Retention in Liquid Phase Sintering of Prealloyed Powders

9610280德国关于超固相线液相烧结(SLPS)的新研究涉及三个主题。第一部分考察了加热和烧结过程中的显微组织演变。目前的过程模型对颗粒生长速率、液膜厚度、收缩速率、半固体颗粒粘度和变形原因进行了假设。通过在模型系统上进行的实验，使用淬火样品的微观结构测量和现场测试，解决了这些假设。目标是增加模型的真实性，并识别系统之间的任何行为。第二个主题是最终部件大小和形状的预测。当液体在晶界上扩散时，结构刚性损失的计算预测需要验证。此外，颗粒大小、颗粒大小、堆积密度、衬底摩擦和热传递方面的梯度需要包括在最终的部件尺寸和形状预测中。第三个活动将模型扩展到其他几个工艺条件(双峰尺寸的粉末、不同组成的粉末、高粘度体系、反应体系)。这项研究的成功将对SLPS工艺的使用产生积极的影响，该工艺通过粉末冶金生产全密度、复杂的形状。一个研究目标是有机会在高性能模具的近净成形生产中使用SLP的工具钢。***

9610280 German New research on supersolidus liquid phase sintering (SLPS) addresses three topics. The first examines microstructural evolution during heating and sintering. A current model of the process makes assumptions on the rate of grain growth, liquid film thickness, shrinkage rate, semisolid particle viscosity, and causes of distortion. These assumptions are addressed by experimentation performed on model systems using microstructure measurements from quenched samples and in situ testing. The goal is to increase the model reality and to recognize any behavior between systems. The second topic is the prediction of final component size and shape. A computational prediction for the loss of structural rigidity as liquid spreads on the grain boundaries needs verification. Furthermore, gradients in grain size, particle size, packing density, substrate friction, and heat transfer need to be included in the final component size and shape predictions. The third activity extends the model to several other processing conditions (bimodal-sized powders, powders of differing compositions, high viscosity systems, reactive systems). %%% Success in this research should positively impact the use of the SLPS process to produce full density, complex shapes via powder metallurgy. A research target is tool steels where there are opportunities to use SLPS in the near net-shape production of high performance tooling. ***