1) Prepare Ca-21.5wt%Ni eutectic alloy by ball milling the required raw powders and melting. Melting temperature: 605 deg C.
2) Pulverize the alloy into powder
3) Next prepare Ni-6wt% Ca eutectic alloy by ball milling the Ca-21.5 Ni alloy powder and nickel powder followed by melting. The melting temperature of this alloy is 1160 deg C.
4) Use these two eutectic alloys to prepare other Ni--Ca alloys.
The above may work in lab scale, not sure about industrial scale.