Abstract aladin is an expert system that aids metallurgists in the design of new aluminum alloys. The system is a hybrid of several artificial intelligence techniques. Declarative representations are used for metallurgical concepts. The design procedure is encoded in a rule-base, with the potential for user participation. The system is based on the hypothesize-and-test model, and a constraint-based search is used to find alternative designs. Strategies are included for resolving the interactions among conflicting subproblems. Metallurgical relationships cover a broad range of symbolic and numerical types of reasoning. In this article, an overview of the project is given, including discussions of knowledge acquisition techniques, design decisions and implementation.