Wachstumskern Thale PM - Verbundprojekt 3: Neue MIM-Werkstoffe. Teilprojekt 4: Entwicklung neuer über das MIM-Verfahren verarbeitbarer heißgaskorrosionsbeständiger Werkstoffe: Abschlussbericht. Laufzeit: 01.11.2008 - 31.10.2011. Förderkennzeichen: 03WKBO03D

The potential market volume and demand of customers for products, which are corrosion resistant at high service temperatures and can be manufactured by the near-net-shape technique of MIM, is constantly growing. Based on MIM parts, which are currently in operation, service temperatures above 850 °C up to 1050 °C are of particular interest. This especially applies to parts turbochargers or turbines. Until the start of this project the MIM process wasn't applied to respective alloys. There is a variety of materials, which were developed for service at high temperatures and corrosive atmospheres. Hot gas corrosion resistance is achieved by the ability of these alloys to form protective layers, which adhere very well on the metal surface. Furthermore, they contain elements, which form precipitates that lead to increased high-temperature strength. However, the oxide layers, wich are formed on the most oxygen-affine elements, lead to constraints in the sintering process. With alloys, which allow operation at temperatures > 850 °C and can be produced by MIM, new applications become possible. The partners of the project "New MIM alloys" agreed on the following aims: 1. Development of hot-corrosion-resistant MIM-processible alloys for temperatures up to 1100 °C. 2. Manufacturing of complex near-net-shape parts of these alloys by MIM with good process reliability. 3. Test of new moulding techniques and increase of process safety of MIM. In parallel process-related questions such as cost efficiency of MIM powders and decreasing the wear of the moulds are investigated. Ni- and Fe-base superalloys were identified, which up to now are not processed by MIM. Starting with conventional alloys the development was done with the focus on heat treatment and characterization. Work was continued with optimized alloys and completely new alloys. It was shown that high Al-containing precipitation-hardened Ni-base superalloys can be produced as tensile bars and turbine wheels. Based on the high-temperature properties (mechanical, oxidation) a service temperature > 850 °C seems possible. Mechanical properties are comparable to those of alternative production routes (HIP, investment casting). ODS (oxide dispersion strengthened) alloys were introduced as a class of materials, which is new to MIM. A patented process route was identified and tested. It was shown that a MIM-processible powder can be produced by high-energy milling. The heat treatment was very complex and only a small amou