The Hot Workability of Alnico 5 and Sendust Alloys

Compression and sheath forging tests were completed at temp. up to 1500 deg K on as-cast Alnico 5 (composition Al 8.59, Ni 14.97, Co 23.0, Cu 3.28%, balance Fe) and Sandust alloys (composition Al 5.91, Si 9.71, Ti 0.84%, balance Fe), which are brittle at temp. above T sub m /2. A large compressive strain, > 1.5, was obtained for Alnico 5 at temp. between 1350 and 1600 deg K and for Sendust at temp. between 1050 and 1500 deg K at a strain rate of 0.0011/s. A homogeneous fine structure was obtained when the alloys were deformed in the ductile range. In the case of Alnico 5 alloy the ductile temp. range was extended by the development of a dual phase structure. Deformability in the ductile temp. range was strongly dependent upon the strain rate; at strain rates > 100/s brittle fracture occurred in all cases. When forging using a mild steel sheathed billet at 1470 deg K and at a strain rate of 1/s, a forging ratio exceeding 7 was obtained for both alloys without cracking.--BA.