PIECE BIMETALLIQUE EN ALLIAGE D'ALUMINIUM COMPORTANT UN INSERT MASSIF EN TITANE OU ALLIAGE DE TITANE

La présente invention concerne des pièces en alliages d'aluminium de fonderie localement renforcées par des inserts massifs en titane ou alliage de titane.Une liaison métallurgique est créée à l'interface entre les deux métaux et cette liaison métallurgique subit sans dommage un cycle de traitement thermique de durcissement structural de l'alliage d'aluminium.Le but global de l'invention est de fabriquer, en minimisant les coûts, des systèmes multifonctionnels complexes plus légers et plus performants que leurs homologues non renforcés. The bimetallic article comprises a cast aluminum alloy and a solid insert made of titanium or its alloy. A continuous metallurgical bond having a tensile strength of at least 150 MPa, determined for a dissected specimen, is produced at the interface of the insert and the aluminum alloy after thermal structural hardening treatment of the latter. Preferred Features: Thermal structural hardening treatment of the aluminum alloy is carried out at 370-540 degrees C for 1-24 hours, typically 4-12 hours, according to the nature of the aluminum alloy and the characteristics of the heat treatment furnace. The thermal treatment does not alter the properties of the metallurgical bond. The titanium alloy is preferably selected from the following series: TA6V, TA5E, TA8DV, Ti.10.2.3., TA6V6E. The insert molding alloy preferably belongs to the series: AS, ASU, AG, AU, AZ and AM. The bimetallic article is produced by gravity casting, compression casting or die casting. The metallurgical bond can be produced during casting, or before casting during a preliminary aluminizing operation, or after casting during thermal structural hardening treatment of the cast alloy. Many titanium or titanium alloy inserts can be inserted in the same article.