The development of advanced materials using novel powder metallurgy processes

Direct powder rolling (DPR) is a process where metallic powders are first compacted into a porous sheet or strip. This strip is then heated in a process known as sintering to allow the individual particles to bond and fuse together. The final step is to cold roll this porous, sintered strip to reduce its thickness and increase its density, ideally removing all the pores. In the case of Titanium and its alloys, the availability of a low-cost powder feedstock, in conjunction with the DPR process, is a potential way to produce lower cost Titanium sheet or foil for a range of industrial applications. However, to date the DPR process applied to Ti powder has not produced sheet with mechanical properties necessary for widespread commercial use. This has limited the use of Titanium in many applications. In this proposal, we will take advantage of unique roll compaction and cold rolling equipment to investigate and optimize the DPR method for producing Ti sheet from low cost powders. The cold rolling mill has the unique capability of measuring the roll force during cold rolling and thickness reduction. This will allow a quantitive study of roll mechanics and densification of porous metals to be completed. The individual rolls in the mill can be rotated at different speeds which allows asymmetric rolling to be performed. It is anticipated that asymmetric rolling will accelerate densification of the porous sheet and create a refined microstructure. Both these features acting together should produce sheets with improved mechanical properties. The fundamental understanding achieved through this research will lead to the development of the relationship between the DPR process, sheet microstructure and mechanical properties. In turn, the work has the potential to break through the current performance barrier of Ti sheet materials derived from low cost powders. This will increase the use of this light metal in the Canadian aerospace and automotive industries, facilitating weight reduction, lower fuel economy and ultimately a reduction in greenhouse gases.