kõrge sulamistemperatuuriga (üle raua sulamistemperatuuri, s.o 1539 °C), peamiselt pulbermetallurgilisel teel valmistatud sulam (vt rasksulavus; vrd kergsulav sulam, kesksulav sulam), an alloy which is: 1. heat resistant or having very high melting point; 2. difficult to work at higher temperatures (see: refractoriness; compare: fusible alloy/low-melting-point alloy, medium-melting-point alloy)