抄録
In this report, structures and mechanical properties were studies for rapidly solidified Ni-Nb-Zr alloys and glassy Fe-based alloys shots with high strength and long life time for shot peening. The results obtained are summarized as follows.
Rapidly solidified Ni-Nb-Zr alloys were formed in a wide composition range of 20 to 75at%Ni, 0 to 60 at%Nb and 0 to 80 at%Zr for formation of amorphous phase, 50 to 70at%Ni, 5 to 35 at%Nb and 5 to 45 at%Zr for formation of glass phase, respectively. The largest value of the supercooled liquid region was 51 K for Ni60Nb20Zr20 alloy. The crystallization temperature (Tx), Vickers hardness (Hv) and fracture strength (σf) of the amorphous (Ni0.5Nb0.5)100-xZrx (x=10, 20, 30 40) alloys were in the rang from 770 to 870 K, 540 to 760 and 1530 to 2300 MPa, respectively. The σf and Hv of the glassy Ni60Nb20Zr20 alloy with the largest supercoold liquid region are 2160 MPa and 700, respectively. The hydrogen permeability of the amorphous (Ni0.6Nb0.4)70Zr30 alloy ribbon was 1.3×10-8 mol/m-1/s-1/Pa-1/2 at 673 K which is slightly larger than that of thin pure Pd metal. Wide ribbons of 50 mm in wide were prepared for the amorphous Ni42Nb28Zr30 and glassy Ni60Nb20Zr20 alloys.
Amorphous/glassy phases with volume fraction exceeding 98% in (Fe, Co, Ni)75B14Si8Mo3 alloy powder with spherical form of about 500μm in diameter were formed with wide composition ranges of 45 to 100at%Fe, 0 to 50at%Co and 5 to 55at%Ni, respectively. Glass transition temperature (Tg), Tx and supercoold liquid region (ΔTx=Tx-Tg) of Fe46Co5Ni24B14Si8Mo3 alloy were 789 K, 833 K and 44 K, respectively. The endurance life time of the glassy Fe-based alloy shots was 4 to 10 times longer than those for the conventional cast steel and high speed steel shots in the same shot peening condition. The maximum value of compressive residual stress in the tool (SKD11) steel shotted were 1600 MPa for the glassy Fe-based alloy shot and 1470 MPa for high speed steel shot, respectively.
