Two-Component Metal Injection Moulding of Ti-6Al-4V and Stainless Steel Bi-Material Parts

Abstract

Two-component metal injection moulding (2C-MIM) allows producing functionally graded metal parts of complex shape by co-sintering. Until now several studies have demonstrated that different material properties can be combined. Another promising material combination is titanium and iron-based materials. It can combine the biocompatibility and low density of titanium with a ductile and cost efficient stainless steel. However, co-sintering these materials reveals challenges due to a significant mismatch in sintering shrinkage and limitations in sintering temperature for both materials. The recent study showed that Ti-6Al-4V can be joined to the stainless steel 316L by 2C-MIM provided that certain constraints are taken in account. The quality of the interface before and after co-sintering is a crucial factor for intact parts after processing. By applying sinterdilatometry the mismatch in shrinkage was compensated by using adjusted powder characteristics and tailored feedstock compositions. A co-sintering cycle was defined with regard to the sintering characteristics of both materials. The developed two-component specimens revealed significant interdiffusion of alloying elements at the Ti-6Al-4V / 316L interface and a tensile strength of 282 MPa after co-sintering.

Powder injection moulding of multi-material devices

“…Studies are already available on two-component PIM in macro and micro dimensions. 3,5,13,14,15 The particular attractiveness, but also challenge, of 2C-PIM consists in obtaining either flexible or permanent joints. For sufficient bond strengths, permanent joints must have defined bonding surfaces between gear wheels and shafts.…”

“…cemented carbides like tungsten carbide. Further applications targeting an increasing market are tungsten copper alloys 20,21,22 to be used for e.g. heat sinks in microelectronic products.…”