Sas vs SATA

Hello,
I have got two hard disk sas but they are old and they start to do “cra cra cra”… this isn’t good.
I would like try WD black but I don’t know if SATA interface is compatible with SAS interface: can I remove sas disk and insert sata drive?
Other question: is there an adapter from NVME to PCIe 2x? I should/could install SO here.
My WS (old but I am upgradimg it): z800 two xeon 5530, 64Gb, GPU k2200, chipset jntel 5520, two hard disk sas and other parts.
Sorry for my bad English
Thank you vefy much